Add CI workflow to check docs (backport #1069)

[mergify]

This is an automatic backport of pull request #1069 done by Mergify.

---

Mergify commands and options

More conditions and actions can be found in the documentation.

You can also trigger Mergify actions by commenting on this pull request:

• @Mergifyio refresh will re-evaluate the rules
• @Mergifyio rebase will rebase this PR on its base branch
• @Mergifyio update will merge the base branch into this PR
• @Mergifyio backport <destination> will backport this PR on <destination> branch

Additionally, on Mergify dashboard you can:

• look at your merge queues
• generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.86%. Comparing base (944c3ac) to head (e113683).

Additional details and impacted files

@@           Coverage Diff           @@
##           humble    #1441   +/-   ##
=======================================
  Coverage   75.86%   75.86%           
=======================================
  Files          41       41           
  Lines        3224     3224           
  Branches     1838     1838           
=======================================
  Hits         2446     2446           
  Misses        414      414           
  Partials      364      364           

Flag	Coverage Δ
unittests	75.86% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.