Update the documentation (ad-m#114)

Author: ZPascal

README.md

@@ -50,6 +50,17 @@ jobs:
 | directory | string | '.' | Directory to change to before pushing. |
 | repository | string | '' | Repository name. <br /> Default or empty repository name represents <br /> current github repository. <br /> If you want to push to other repository, <br /> you should make a [personal access token](https://github.com/settings/tokens) <br /> and use it as the `github_token` input.  |
 
+## Troubeshooting
+
+Please be aware, if your job fails and the corresponding output log looks like the following error, update your used verson of the action to `ad-m/github-push-action@master`:
+```log
+Push to branch ***************
+fatal: unsafe repository ('/github/workspace' is owned by someone else)
+To add an exception for this directory, call:
+
+	git config --global --add safe.directory /github/workspace
+```
+
 ## License
 
 The Dockerfile and associated scripts and documentation in this project are released under the [MIT License](LICENSE).