Accept version strings in dot separated format.

[ndm2]

This allows to use version strings like 4.next instead of 4-next for the search_version docs theme config option, unifying the format used in all the different places, so no special format has to be remembered.

This change is backwards compatible, the various docs config files can be updated once this change is live and there should be no downtime.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ce6b947) to head (9cd21f8).
⚠️ Report is 11 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #16 +/- ##
===========================================
Coverage 100.00% 100.00% Complexity 67 67 ===========================================
Files 6 6 Lines 282 282 ===========================================
Hits 282 282 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.