Publish documentation on readthedocs

[nicoddemus]

• [ ] Extract documentation from docstrings and publish on readthedocs;
• [x] Add proper install and usage instructions;
• [x] Craft a minimal complete example of the usage;
• [ ] Fix documentation build;
• [ ] Check and update examples;
• [ ] Investigate a better layout for the "reference" section;
• [ ] Improve in auto generated documentation;
• [ ] Extent example list with ... (we should list more advanced features and create a item for each one);

Suggestion for new items are welcome.