Merge pull request #168 from oakmound/feature/drop-develop

oak: update contributing to note develop being dropped

CONTRIBUTING.md

@@ -1,6 +1,4 @@
 # Contributing
+
 Please raise issues for discussion before making significant pull requests to
 packages not under `oak/entities/x`.
-
-Pull requests that are more than documentation / superficial changes should be
-directed to `develop` to later be merged into `master` with a release number.