Improve developer's guide

[jorgepiloto]

💻 Feature request: developer's guide

The current developer's guide only provides information on how to setup the development environment.

However, there are several things which might be useful to document:

• The type of naming convention we follow in the project, same as Python one
• The git branch naming convection: branches must be named like issue_label/single_word to better track those.

If you find require from any additional style-guide convention, please suggest it within the comments sections below.

[jorgepiloto]

Moving this to the next release, so the 0.1 is ready before the presentation in the ICATT 8th Edition.

[jorgepiloto]

Everything is going to be collected in the right metadata file CONTRIBUTING. No more docs. This is a trivial library. Pure functions solving just one problem.