Add release documentation in DEVELOPMENT.rst

CHANGES.rst

@@ -1,6 +1,11 @@
 Changes
 =======
 
+unreleased
+----------
+
+* add development documentation in development.rst
+
 0.5.1 - 2021-09-04
 ------------------
 

DEVELOPMENT.rst

@@ -0,0 +1,47 @@
+Development
+===========
+
+The extension is developed in a git repository that can be cloned by running::
+
+    git clone https://git.dittberner.info/jan/sphinxext-ip.git
+
+Running test
+------------
+
+To install all dependencies and run the tests use::
+
+    pipenv install --dev
+    pipenv run pytest
+
+Release a new version
+---------------------
+
+Start by deciding the new release number and perform the following steps:
+
+* update CHANGES.rst
+* change ``version`` in setup.cfg
+* change ``__version__`` in jandd/sphinxext/ip.rst
+* change ``version`` in tests/root/conf.py
+* commit and push your changes ::
+
+     git commit -m "Release <version>"
+     git push
+
+* create an annotated and signed tag with the new version number (``git
+  shortlog <previous_tag>..HEAD`` could help to create a good release tag
+  message) ::
+
+     git tag -s -a 0.5.1
+
+* build the release artifacts ::
+
+     rm -rf dist jandd.sphinxext.ip.egg-info
+     pipenv run python3 setup.py egg_info -b <version< bdist_wheel sdist
+
+* upload to PyPI using twine ::
+
+     pipenv run twine upload -s dist/*
+
+* push the tag to git ::
+
+     git push --tags