docs: try autobuild for local dev

[Borda]

What does this PR do?

This could be an exciting feature for faster interaction during local development, ref: https://github.com/sphinx-doc/sphinx-autobuild

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

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📚 Documentation preview 📚: https://torchmetrics--2518.org.readthedocs.build/en/2518/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69%. Comparing base (1baf920) to head (b328c19).
Report is 90 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #2518   +/-   ##
======================================
  Coverage      69%     69%           
======================================
  Files         329     329           
  Lines       18077   18077           
======================================
  Hits        12499   12499           
  Misses       5578    5578           

[Borda]

@baskrahmer, have you tried this one, and do you see the difference? :)

[Borda]

hit this issue sphinx-doc/sphinx-autobuild#155 (comment)
let's wait until sphinx-doc/sphinx-autobuild#157 is released

[Borda]

another complication described in sphinx-doc/sphinx-autobuild#162