EUG - Improve End User guide: "2.2. Version Control" section

Doc link http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Devtools/job/doc-CodeReady-Workspaces_End-user-Guide/lastSuccessfulBuild/artifact/index.html#version-control_crw

===== 2.2.1. Managing Git configuration: identity:

1)
> Prerequisites .
>The Visual Studio Code Git extension installed.
Remove this since Visual Studio Code Git extension is embedded in Theia

2)
> 1. Open File > Settings > Open Preferences
Outdated screenshot

3)
>In the opened window, navigate to the Git section, and find:
>user.name
>user.email
It is not correct. The UI fields is present and has different names.
user.name and user.email are values of json config file under git section (so whole option is git.user.name and git.user.email). This makes sense, but we should clearly say that we are talking about raw json config file.

4)
>To configure Git identity using the command line, open the terminal of the Che-Theia container.
It is confusing. We have to point out, that is user would like to use git from the console he has to configure Git identity using the command line. More over if OAuth is used then git username and email are already configured.

===== 2.2.2. Accessing a Git repository using HTTPS

6)
>Prerequisites
> The git tool is available. See: Getting Started - Installing Git.
Remove this, Theia container has git installed already.

7)
> Red Hat CodeReady Workspaces supports Git self-signed TLS certificates. See link: LINK IS BROKEN (both format and destination)

===== 2.2.3. Accessing a Git repository using a generated SSH key pair

8)
> Prerequisites
> A running instance of CodeReady Workspaces. To install an instance of Red Hat CodeReady Workspaces, see
LINK IS NOT CORRECT

9)
> Click the View button and copy the public key from the editor and add it to the Git provider.
We should say that the "View" button is on notification in bottom right corner.

10) Doc doesn't mention that to use generated key in all containers it is needed to restart the workspace.

11)
> Because of this action,
Fix English.

===== 2.2.4. Managing pull requests using the GitHub PR plug-in

12)
> Using the GitHub Pull Requests plug-in
The plugin is not installed and the commands is not available. So whole section not relevant.

15)
> Authenticate by running the GitHub authenticate command.
Where to run the command? It is not clear (Probably in command palette but the command is absent there)