[FEATURE] Add how-to to change commit author

Author: pixelbrackets

git_cheat_sheet.md

@@ -123,10 +123,16 @@
 		git commit
 		git commit -m "<message>"
 
-* Change the last commit
+* Change the last commit 
 
 		git commit --amend -a
 
+	_This will replace the last commit (new ID), so it should only be used if the modified branch was not pushed yet_
+
+* Special: Change author of the last commit
+
+		git commit --amend --author "John Doe <[email protected]>" 
+
 ## Branches
 
 * List local branches