Added Git Cheat Sheet by GitLab (#6422)

more/free-programming-cheatsheets.md

@@ -78,6 +78,7 @@
 ### Git
 
 * [Git Cheat Sheet](https://education.github.com/git-cheat-sheet-education.pdf) - GitHub (PDF)
+* [Git Cheat Sheet](https://about.gitlab.com/images/press/git-cheat-sheet.pdf) - GitLab (PDF)
 * [Git Cheat Sheet](http://git.jk.gs) - Jan Krüger (PDF, SVG)
   * [Git Cheat Sheet](https://jan-krueger.net/wordpress/wp-content/uploads/2007/09/git-cheat-sheet.pdf) (PDF)
   * [Git Cheat Sheet - extended](https://jan-krueger.net/wordpress/wp-content/uploads/2007/09/git-cheat-sheet-v2.zip) (PDF)