#23 Document git-extras

README.md

@@ -18,6 +18,12 @@ Your development workstation needs to be prepared once, so that Docker and its c
   sudo pip install docker-compose
   ```
 
+- [Install Git Extras](https://github.com/tj/git-extras/blob/master/Installation.md)
+
+  ```bash
+  sudo apt-get install git-extras
+  ```
+
 - Name the group and add your user to it
 
   ```bash