Docs: improve description

Author: JPeer264

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://travis-ci.org/JPeer264/node-git-needs-push.svg?branch=master)](https://travis-ci.org/JPeer264/node-git-needs-push)
 
-Check synchronously if a git repository needs to push
+Check synchronously if a git repository needs to push. If a branch is just local it will be `true` (as a push is required)
 
 ## Installation