Added 'Atlassian Git Cheatsheet' (#7190)

* Added Git Cheatsheet

* Reverting superfluous added newlines

Resolves some of linter warnings

* fix resource info

* Add PDF format note

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

more/free-programming-cheatsheets.md

@@ -110,6 +110,7 @@
 * [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)
+* [Git cheat sheet](https://www.atlassian.com/git/tutorials/atlassian-git-cheatsheet) - Atlassian (PDF)
 * [Git Cheat Sheet](https://programmingwithmosh.com/wp-content/uploads/2020/09/Git-Cheat-Sheet.pdf) - Moshfegh Hamedani (PDF)
 * [Git ściąga (pl)](https://training.github.com/downloads/pl/github-git-cheat-sheet/) - GitHub
 * [GitHub Actions Security Best Practices \[cheat sheet included\]](https://blog.gitguardian.com/github-actions-security-cheat-sheet/) - Thomas Segura, GitGuardian, C.J. May (online, PDF)