list merged branches

Useful when you need to know which branches you can delete.

Author: juanpabloaj

README.md

@@ -503,6 +503,11 @@ $ git mergetool
 $ git merge <branch>
 ```
 
+#### List merged branches
+```
+$ git branch --merged
+```
+
 ##### Rebase your current HEAD onto &lt;branch&gt;:<br>
 <em><sub>Don't rebase published commit!</sub></em>