Reorganise documentation & usage example

[n-peugnet]

• Move Quick Sample into its own usage.rst page of the doc, as it is only correctly rendered in a Sphinx documentation.
• Move Changelog inclusion into its own page of the doc, as its growing size took a lot of space in the home page.

These two changes leave a lot more room for the table of contents, as it was quite buried in the home page before.

Fixes #41

[markstory]

Thank you 🎉