Update releasing docs (#120)

I failed to find the release docs under docs - our other repos keep them in RELEASING.md. So, move them to the conventional place, and update them with the notes I made during the release of v0.1.5.

Author: richvdh

MANIFEST.in

@@ -1,9 +1,9 @@
 include *.in
 include *.py
+include *.md
 include LICENSE
 include tox.ini
 include requirements.txt
 include .coveragerc
 include .codecov.yml
 recursive-include tests *.py
-recursive-include docs *.md

RELEASING.md

@@ -0,0 +1,45 @@
+# How to release `matrix-synapse-ldap3`
+
+Releasing `matrix-synapse-ldap3` involves bumping the version number, creating
+a new tag on Github, then uploading release packages to
+[PyPi](https://pypi.org).
+
+You will need push access to this repo as well as an account on PyPi with push
+access to the
+[matrix-synapse-ldap3](https://pypi.org/project/matrix-synapse-ldap3/) package.
+
+1. Edit the `__version__` variable of `ldap_auth_provider.py` to the new release
+version. This repository uses [Semantic Versioning](https://semver.org/).
+
+1. Set a variable to the version number for convenience:
+   ```sh
+   ver=$(python3 -c 'import ldap_auth_provider; print(ldap_auth_provider.__version__)')
+   ```
+
+1. Push your changes:
+   ```sh
+   git add -u && git commit -m $ver && git push
+   ```
+
+1. Create a signed git tag for the release:
+   ```sh
+   git tag -s v$ver
+   ```
+
+   Set the first line of the message to `vX.Y.Z`, and the rest to the changes since the last release (hint: `git log --pretty=%s --reverse v<old ver>...`)
+
+1. Push the tag:
+   ```sh
+   git push origin tag v$ver
+   ```
+
+1. Build and upload to PyPI:
+   ```sh
+   python setup.py sdist
+   twine upload dist/matrix-synapse-ldap3-$ver.tar.gz
+   ```
+
+1. Create release on GH project page:
+   ```sh
+   xdg-open https://github.com/matrix-org/matrix-synapse-ldap3/releases/edit/v$ver
+   ```