[Documentation] Adding "push" behaviour to README

[nbrugger-tgm]

At the current readme users cannot see if the commit is pushed to the given ref or just commited locally.

If the commit is pushed please add a note that also tells it, if not please also add a note long the lines of:

> This action does not push the commit, to push the commit to your PR use 
> ```yml
> - name: Push commit
>   run: git push
> ```

[nbrugger-tgm]

Created a PR (#10 )