Stream line information on how to get sources

- come straight to point: how to clone (don't talk about git config)
- refer to contributing documentation where necessary instead of
  repeating information

doc/GET_SOURCES.md

-The OpenAirInterface software can be obtained from our gitLab
-server. You will need a git client to get the sources. The repository
-is currently used for main developments.
+The OpenAirInterface software can be obtained from our gitLab server. You will
+need a git client to get the sources. The repository is used for main
+developments.
 
 # Prerequisites
 
-You need to install git using the following commands:
+You need to install `git` using the following commands:
 
 ```shell
 sudo apt-get update
 sudo apt-get install git
 ```
 
-# Using EURECOM Gitlab
+# Clone the Git repository (for OAI Users without login to gitlab server)
 
 The [openairinterface5g repository](https://gitlab.eurecom.fr/oai/openairinterface5g.git)
 holds the source code for the RAN (4G and 5G).
 
-Configure git with your name/email address (only important if you are developer and want to contribute/push code to Git Repository):
+## All users, anonymous access
+
+Clone the RAN repository:
 
 ```shell
-git config --global user.name "Your Name"
-git config --global user.email "Your email address"
+git clone https://gitlab.eurecom.fr/oai/openairinterface5g.git
 ```
 
-## In order to clone the Git repository (for OAI Users without login to gitlab server)
+## For contributors
 
-Cloning RAN repository:
+Configure git with your name/email address, important if you are developer and
+want to contribute by pushing code. Please put your full name and the e-mail
+address you use in Gitlab.
 
 ```shell
-git clone https://gitlab.eurecom.fr/oai/openairinterface5g.git
+git config --global user.name "Your Name"
+git config --global user.email "Your email address"
 ```
 
-## In order to contribute to the Git RAN repository (for OAI Developers/admins with login to gitlab server)
-
-Please send email to [contact@openairinterface.org](mailto:contact@openairinterface.org) to be added to the repository
-as a developer (only important for users who want to commit code to the repository). If
-you do not have account on gitlab.eurecom.fr, please register yourself to gitlab.eurecom.fr and provide the login name in the email.
-
-More information can be found in [a separate page](../CONTRIBUTING.md).
+More information can be found in [the contributing page](../CONTRIBUTING.md).
 
 # Which branch to checkout?
 
-`develop`: contains recent commits that are tested on our CI test bench. The update frequency is about once a week. 5G is only in this branch. It is the recommended  and default branch.
-`master`: contains a stable version of 4G, and will be updated in the future with 5G.
+- `develop`: contains recent commits that are tested on our CI test bench. The
+  update frequency is about once a week. 5G is only in this branch. **It is the
+  recommended and default branch.**
+- `master`: contains a known stable version.
 
-Please see the work flow and policies page: https://gitlab.eurecom.fr/oai/openairinterface5g/wikis/oai-policies-home
-
-You can find the latest stable tag release here: https://gitlab.eurecom.fr/oai/openairinterface5g/tags
+You can find the latest stable tag release here:
+https://gitlab.eurecom.fr/oai/openairinterface5g/tags
 
 The tag naming conventions are:
 
-- On `master` branch: **v1.`x`.`y`** where
-  * `x` is the minor release number, incremented every 2-3 months when we are merging `develop` into `master` branch.
-  * `y` is the maintenance number, starting at 0 when we do a minor release and being incremented when a bug fix is incorporated into `master` branch.
+- On `master` branch: **v`x`.`y`.`z`**
 - On `develop` branch **`yyyy`.w`xx`**
   * `yyyy` is the calendar year
   * `xx` the week number within the year
+
+More information on work flow and policies can be found in [this
+document](./code-style-contrib.md).