Add contributing guide

Author: kynan

CONTRIBUTING.rst

@@ -0,0 +1,27 @@
+How to contribute
+=================
+
+Development happens on GitHub_ - `bug reports`_ and `pull requests`_ welcome!
+
+Releasing a new version
+-----------------------
+
+To simplify updating the version number consistently across different files
+and creating the appropriate annotated tag, we use bump2version_. For a new
+patch release, run ::
+
+    bump2version patch
+
+and for a minor release ::
+
+    bump2version minor
+
+Remember to also push the release tag with ``git push --tags``.
+
+Use twine_ to upload the new release to PyPI.
+
+.. _GitHub: https://github.com/kynan/dokuwikixmlrpc
+.. _bug reports: https://github.com/kynan/dokuwikixmlrpc/issues
+.. _pull requests: https://github.com/kynan/dokuwikixmlrpc/pulls
+.. _bump2version: https://github.com/c4urself/bump2version
+.. _twine: https://twine.readthedocs.io/en/latest/#using-twine