doc(release): prepare for v2.0.0

Signed-off-by: Raphael Defosseux <raphael.defosseux@openairinterface.org>

CHANGELOG.md

 # RELEASE NOTES: #
 
+## v2.0.0 -- December 2023 ##
+
+* Features
+  - Support YAML configuration file
+    * Yaml validation default value
+  - Implemented an eBPF-based solution in parallel of the current Simple-Switch solution
+    * This is a runtime option
+  - De-register towards NRF on exit
+  - Enable PFCP association request for no NRF case
+* Tech debt
+  - Switching to clang-format-12
+  - Published image on Docker-Hub is using now Ubuntu-22 as base image
+  - Ubuntu-18 is no longer supportable due to eBPF
+
+## v1.5.1 -- May 2023 ##
+
+* Support for rocky linux 8.7
+* Increasing size of hashmap tables
+* Code Refactoring for:
+  * Logging mechanism (runtime log level selection)
+* Published image on Docker-Hub is using now Ubuntu-20 as base image
+  * We will soon obsolete the build system for Ubuntu18.04
+
 ## v1.5.0 -- January 2023 ##
 
 * feat(fqdn): giving some time for FQDN resolution

CONTRIBUTING.md

-# Contributing to OpenAir-CN #
+# Contributing to OpenAir-CN-5G #
 
 We want to make contributing to this project as easy and transparent as possible.
 
 Please refer to the steps described on our website: [How to contribute to OAI](https://www.openairinterface.org/?page_id=112)
 
 1. Sign and return a Contributor License Agreement to OAI team.
-2. Create an account on [Eurecom GiLab Server](https://gitlab.eurecom.fr/users/sign_up)
+2. Create an account on [Eurecom GiLab Server](https://gitlab.eurecom.fr/users/sign_in) if you do not have any.
    - If your email domain (`@domain.com`) is not whitelisted, please contact us (mailto:contact@openairinterface.org).
    - Eurecom GitLab does NOT accept public email domains.
-3. Provide the identifiant of this account to the OAI team (mailto:contact@openairinterface.org) so you have developer rights on this repository.
+3. Provide the `username` of this account to the OAI team (mailto:contact@openairinterface.org) so you have developer rights on this repository.
 4. The policies are described in these wiki pages: [OAI Policies](https://gitlab.eurecom.fr/oai/openairinterface5g/wikis/oai-policies-home)
    - You can fork onto another hosting system. But we will **NOT** accept a pull request from a forked repository.
       * This decision was made for the license reasons.
@@ -32,13 +32,16 @@ If the synchronization fails, you may need to go into the path of the failing gi
 
 We are using `clang-format` as formatting tool on the C/C++ code.
 
-At the time of writing (Jubeh 20th, 2023), we are using `clang-format` version 12.0.0.
+At the time of writing (September 27th, 2023), we are using `clang-format` version 12.0.0.
 
-On a Ubuntu20+ server, to install:
+On a Ubuntu-20/22 server:
 
 ```bash
-sudo apt-get install -y clang-format-12
-sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-12 20
+$ sudo apt-get update
+$ sudo apt-get install clang-format-12 dos2unix
+$ sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-12 20
+$ clang-format --version
+Ubuntu clang-format version 12.0.0-3ubuntu1~20.04.5
 ```
 
 How to format:
@@ -46,6 +49,7 @@ How to format:
 ```bash
 $ cd myClonedWorkspace/src
 $ clang-format -i theFilesYouWantToFormat
+$ dos2unix theFilesYouWantToFormat
 ```
 
 ## License ##
@@ -56,7 +60,7 @@ By contributing to OpenAirInterface, you agree that your contributions will be l
 
 1.  You push your modified code with the new branch onto our [official GitLab repository](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf).
     -  Please make the name of the branch explicit and short.
-2.  You create a merge request from the [dedicated web page](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf/-/merge_requests).
+2.  You create a pull request from the [dedicated web page](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf/-/merge_requests).
     -  The `target` (`base` in the web-page) branch **SHALL be `develop`**.
     -  The `source` (`compare` in the web-page) branch is your branch.
 3.  Our Continuous Integration (CI) process will be triggered automatically on your proposed modified code and check the validity.
@@ -69,7 +73,7 @@ By contributing to OpenAirInterface, you agree that your contributions will be l
     -  That will allow fairness on the CI usage to other contributors.
 4.  When this automated process passes, one of our CI administrators will review your changes or assign a senior contributor
   to do a peer-review.
-5.  Once the peer reviewer accepts your modification, one of our CI administrators will accept and merge your merge request
+5.  Once the peer reviewer accepts your modification, one of our CI administrators will accept and merge your pull request
     -  The CI will run again on the new `develop` branch commit.
     -  The source branch WILL be deleted by one of our CI administrators.
 

README.md

-<h1 align="center">
-    <a href="https://openairinterface.org/"><img src="https://openairinterface.org/wp-content/uploads/2015/06/cropped-oai_final_logo.png" alt="OAI" width="550"></a>
-</h1>
-
 ------------------------------------------------------------------------------
 
-                             OPENAIR-CN
-    An implementation of the Evolved Packet Core network.
-    
+                             OPENAIR-CN-5G
+ An implementation of the 5G Core network by the OpenAirInterface community.
+
 ------------------------------------------------------------------------------
-    
-<p align="center">
-    <a href="https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf/-/blob/master/LICENSE"><img src="https://img.shields.io/badge/license-OAI--Public--V1.1-blue" alt="License"></a>
-    <a href="https://jenkins-oai.eurecom.fr/job/OAI-CN5G-UPF/"><img src="https://img.shields.io/jenkins/build?jobUrl=https%3A%2F%2Fjenkins-oai.eurecom.fr%2Fjob%2FOAI-CN5G-UPF%2F&label=build%20OAI-UPF"></a>
-</p>
-
-  Openair-cn is an implementation of the 3GPP specifications concerning the 
-  Evolved Packet Core Networks, that means it contains the implementation of the
-  following network elements:
-
-  * MME,
-  * HSS,
-  * S-GW+P-GW.
+
+OPENAIR-CN-5G is an implementation of the 3GPP specifications for the 5G Core Network.
+At the moment, it contains the following network elements:
+
+* Access and Mobility Management Function (**AMF**)
+* Authentication Server Management Function (**AUSF**)
+* Location Management Function (**LMF**)
+* Network Exposure Function (**NEF**)
+* Network Slicing Selection Function (**NSSF**)
+* Network Repository Function (**NRF**)
+* Network Data Analytics Function (**NWDAF**)
+* Policy Control Function (**PCF**)
+* Session Management Function (**SMF**)
+* Unified Data Management (**UDM**)
+* Unified Data Repository (**UDR**)
+* Unstructured Data Storage Function (**UDSF**)
+* User Plane Function (**UPF**)
   
-  Each element implementation has its own repository: this repository (`oai-upf`) is meant for UPF.
+Each element implementation has its own repository: this repository (`oai-upf`) is meant for UPF.
 
-# oai-upf
+# Licence info
 
-In the `Control / User Planes Separation` (a.k.a. `CUPS`) of SPGW, only the UPF (User Plane) implementation is available in this repo.
+It is distributed under `OAI Public License V1.1`.
+See [OAI Website for more details](https://www.openairinterface.org/?page_id=698).
 
-This component can be deployed:
+The text for `OAI Public License V1.1` is also available under [LICENSE](LICENSE)
+file at the root of this repository.
 
-*  As first intended as `4G-LTE` Core Network User Plane function.
-*  But now also as a `5G` Core Network User Plane function (a.k.a. `UPF`)
+# Where to start
 
-It is distributed under `OAI Public License V1.1`. See [OAI Website for more details](https://www.openairinterface.org/?page_id=698).
+The Openair-CN-5G UPF code is written, executed, and tested on UBUNTU server focal/jammy version.
+Other Linux distributions support will be added later on.
 
-The text for `OAI Public License V1.1` is also available under [LICENSE](LICENSE) file in the same directory.
+More details on the supported feature set is available on this [page](docs/FEATURE_SET.md).
 
-# Where to start
+# Collaborative work
 
-  The Openair-cn UPF code is written, executed, and tested on `UBUNTU` server `bionic` version.
+This source code is managed through a GITLAB server, a collaborative development platform:
 
-  It is also built and tested on `RHEL8` platform (such as `Openshift`).
+*  URL: [https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-upf).
 
-  More details on the deployment options and the supported feature set is available on this [page](docs/FEATURE_SET.md).
+Process is explained in [CONTRIBUTING](CONTRIBUTING.md) file.
 
-# Collaborative work
+# Contribution requests
+
+In a general way, anybody who is willing can contribute on any part of the
+code in any network component.
+
+Contributions can be simple bugfixes, advices and remarks on the design,
+architecture, coding/implementation.
 
-  This source code is managed through a GitLab, a collaborative development platform
+# Release Notes
 
-  Process is explained in [CONTRIBUTING](CONTRIBUTING.md) file.
+They are available on the [CHANGELOG](CHANGELOG.md) file.
 
 # Directory structure