[doc framework] Assert that the good and bad example exists in the doc

[Pierre-Sassoulas]

Type of Changes

	Type
✓	📜 Docs

Description

Following #9933 that closed #5953, we're now able to check that we have a good example and a bad example. Some message need to be permitted to not have examples. This permitted to catch a typo in the doc (unrecognize-option) but we could check that no directory that shouldn't exists do, too.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.80%. Comparing base (0950916) to head (b40b1d2).
Report is 80 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9936   +/-   ##
=======================================
  Coverage   95.80%   95.80%           
=======================================
  Files         174      174           
  Lines       18933    18933           
=======================================
  Hits        18139    18139           
  Misses        794      794