[DOP-13156] Documentation improvements

[dolfinus]

Change Summary

• Added third-party HWM Store links to Readme, like YAMLHWMStore in onETL and HorizonHWMStore
• Added documentation for HWMStoreStackManager and HWMStoreClassRegistry methods
• Fixed old examples in HWMTypeRegistry methods
• Updated example of @detect_hwm_store
• Renamed HWMStoreClassRegistry.known_types to aliases, new name should be more descriptive. This is breaking change, but really nobody calls this method explicitly.
• Moved nesting from HWM and HWM Store sections of menu:

Before

After

See https://etl-entities--79.org.readthedocs.build/en/79/

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (94b4af0) 96.45% compared to head (0053679) 96.45%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #79   +/-   ##
========================================
  Coverage    96.45%   96.45%           
========================================
  Files           50       50           
  Lines         1129     1129           
  Branches       202      202           
========================================
  Hits          1089     1089           
  Misses          23       23           
  Partials        17       17           

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