Update documentation on how to get sources

doc/GET_SOURCES.md

-<table style="border-collapse: collapse; border: none;">
-  <tr style="border-collapse: collapse; border: none;">
-    <td style="border-collapse: collapse; border: none;">
-      <a href="http://www.openairinterface.org/">
-         <img src="./images/oai_final_logo.png" alt="" border=3 height=50 width=150>
-         </img>
-      </a>
-    </td>
-    <td style="border-collapse: collapse; border: none; vertical-align: center;">
-      <b><font size = "5">The OpenAirInterface repository: the sources</font></b>
-    </td>
-  </tr>
-</table>
-
 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.
 
 # Prerequisites
 
-You need to install the subversion/git using the following commands:
+You need to install git using the following commands:
 
 ```shell
 sudo apt-get update
-sudo apt-get install subversion git
+sudo apt-get install git
 ```
 
 # Using EURECOM Gitlab
 
 The [openairinterface5g repository](https://gitlab.eurecom.fr/oai/openairinterface5g.git)
-holds the source code for (eNB RAN + UE RAN).
-
-For legal issues (licenses), the core network (EPC) source code is now moved away from
-the above openairinterface5g git repository.
-
-*  A more recent version is available under our GitHub domain:
-   *  [OAI GitHub openair-cn domain](https://github.com/OPENAIRINTERFACE)
-   *  Check its wiki pages for more details
+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):
 
@@ -44,18 +23,6 @@ git config --global user.name "Your Name"
 git config --global user.email "Your email address"
 ```
 
-- Add a certificate from gitlab.eurecom.fr to your Ubuntu 14.04 installation:
-
-```shell
-echo -n | openssl s_client -showcerts -connect gitlab.eurecom.fr:443 2>/dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | sudo tee -a /etc/ssl/certs/ca-certificates.crt
-```
-
-- Disable certificate check completely if you do not have root access to /etc/ssl directory
-
-```shell
-git config --global http.sslverify false
-```
-
 ## In order to clone the Git repository (for OAI Users without login to gitlab server)
 
 Cloning RAN repository (eNB RAN + UE RAN):
@@ -70,13 +37,6 @@ Please send email to [contact@openairinterface.org](mailto:contact@openairinterf
 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 identifiant in the email.
 
-* Clone with using ssh keys:
-   * You will need to put your ssh keys in https://gitlab.eurecom.fr/profile/keys
-     to access to the git repo. Once that is done, clone the git repository using:
-   * `git clone git@gitlab.eurecom.fr:oai/openairinterface5g.git`
-* Clone with user name/password prompt:
-   * `git clone https://YOUR_USERNAME@gitlab.eurecom.fr/oai/openairinterface5g.git`
-
 # Which branch to checkout?
 
 On the RAN side:
@@ -84,15 +44,15 @@ On the RAN side:
 * **master**: This branch is targeted for the user community. Since January 2019, it is also subject to a Continuous Integration process. The update frequency is about once every 2-3 months. We are also performing bug fixes on this branch.
 * **develop**: This branch contains recent commits that are tested on our CI test bench. The update frequency is about once a week.
 
-Please see the work flow and policies page :
+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 :
+you can find the latest stable tag release here:
 
 https://gitlab.eurecom.fr/oai/openairinterface5g/tags
 
-The tag naming conventions are :
+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.