docs: List `DJANGOCMS_VERSIONING_LOCK_VERSIONS` in settings

[fsbraun]

Description

This PR updates the docs , specifically explicitly lists the DJANGOCMS_VERSIONING_LOCK_VERSIONS settings in settings.rst.

It also introduces a github action that builds the docs.

Related resources

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Checklist

• [x] I have opened this pull request against master
• [x] I have added or modified the tests when changing logic
• [x] I have followed the conventional commits guidelines to add meaningful information into the changelog
• [x] I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e6e3143) 90.93% compared to head (187c8ef) 90.93%.

:exclamation: Current head 187c8ef differs from pull request most recent head e1096af. Consider uploading reports for the commit e1096af to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #350 +/- ## ======================================= Coverage 90.93% 90.93% ======================================= Files 72 72 Lines 2536 2536 Branches 357 357 ======================================= Hits 2306 2306 Misses 170 170 Partials 60 60 ```

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