Document how to release a new package version

RELEASE.md

@@ -0,0 +1,24 @@
+## Release process
+
+First install development dependencies. Make sure you're on `master` branch with all changes that are going to be released.
+
+```
+pip install -e '.[dev]'
+```
+
+Then run `bumpversion part` to bump version of the script. `part` may be either `patch`, `minor` or `major`, decide
+which one to use according to [semantic versioning](https://semver.org/). `bumpversion` will bump script's version
+in files inside repository, commit the changes and tag the commit with `vX.Y.Z` tag, where `X.Y.Z` is the current
+version of the script. Now push the commit and the tag.
+
+```
+git push origin && git push origin vX.Y.Z
+```
+
+The new version has already been tagged in `git` repository, now it's time to release a new version on [PyPI](https://pypi.org/project/packt/). Run `python setup.py sdist` to build the package for the new release, check if build was successful by running `twine check dist/*`. If everything is alright run
+
+```
+twine upload dist/*
+```
+
+to release a new version to PyPI.

setup.py

@@ -14,10 +14,12 @@
 ]
 
 dev_requirements = [
+    'bumpversion==0.5.3',
     'mccabe==0.6.1',
     'pycodestyle==2.5.0',
     'pyflakes==2.1.1',
-    'pylama==7.7.1'
+    'pylama==7.7.1',
+    'twine==1.15.0'
 ]
 
 setup(