[MISC] Documentation imported from Discourse

[deusebio]

Issue

The documentation on Discourse is out of sync.
The automated Discourse->GitHub sync system is still WIP, so we need to sync docs on manual request.

Solution

The sync tool created by @deusebio is able to create PR from Discourse to GitHub,
but it requires manual post-production to avoid mermaid diagrams removal from GitHub.
we have to update automated PRs manually until we are waiting for mermaid support on Discource:
canonical/charmhub.io#1525

[codecov]

Codecov Report

Merging #211 (9821854) into main (81adb5a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #211   +/-   ##
=======================================
  Coverage   65.40%   65.40%           
=======================================
  Files          12       12           
  Lines        2139     2139           
  Branches      269      269           
=======================================
  Hits         1399     1399           
  Misses        654      654           
  Partials       86       86