README: removed develop mentions

.github/CONTRIBUTING.md

@@ -9,9 +9,7 @@ and help.
 
 If you'd like to contribute to go-ethereum please fork, fix, commit and
 send a pull request. Commits which do not comply with the coding standards
-are ignored (use gofmt!). If you send pull requests make absolute sure that you
-commit on the `develop` branch and that you do not merge to master.
-Commits that are directly based on master are simply ignored.
+are ignored (use gofmt!).
 
 See [Developers' Guide](https://github.com/ethereum/go-ethereum/wiki/Developers'-Guide)
 for more details on configuring your environment, testing, and