Remove GitHub Desktop installation instructions

Github Desktop does not bundle Git.

- desktop/desktop#12051
- desktop/desktop#18234

This documentation hasn't been fixed for 4 and a half years.

Author: eamonburns

git-guides/install-git.md

@@ -13,10 +13,6 @@ To see if you already have Git installed, open up your terminal application.
 
 Once you've opened your terminal application, type `git version`. The output will either tell you which version of Git is installed, or it will alert you that `git` is an unknown command. If it's an unknown command, read further and find out how to install Git.
 
-## Install Git Using GitHub Desktop
-
-Installing GitHub Desktop will also install the latest version of Git if you don't already have it. With GitHub Desktop, you get a command-line version of Git with a robust GUI. Regardless of if you have Git installed or not, GitHub Desktop offers a simple collaboration tool for Git. You can [learn more here](https://desktop.github.com/).
-
 ## Install Git on Windows
 
 1. Navigate to the latest [Git for Windows installer](https://gitforwindows.org/) and download the latest version.