Add guideline of tasks required to publish a new version

This guideline will be helpful to future maintainers.

We will be able to write it after the release of the first version: 0.2

Expected tasks to execute before:

1. update the release notes
2. merge develop into master
3. create git tag
   • authorized names for release candidates: M.m(.p)rcwhatever (https://packaging.python.org/guides/distributing-packages-using-setuptools/#standards-compliance-for-interoperability)
   • tag version should match __meta__.version
4. push to pypi
5. announce

And then

6. Update __meta__.version to match the next expected release number in develop branch