docs: adding PESQ example to gallery

[Borda]

What does this PR do?

adding another sample

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?

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📚 Documentation preview 📚: https://torchmetrics--2755.org.readthedocs.build/en/2755/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70%. Comparing base (a8cbae7) to head (a971d3c).
Report is 1 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #2755   +/-   ##
======================================
  Coverage      70%     70%           
======================================
  Files         336     336           
  Lines       18231   18231           
======================================
  Hits        12707   12707           
  Misses       5524    5524           

[SkafteNicki]

@Borda what is missing here?

[Borda]

what is missing here?

I was not sure if the story is rich enough

[SkafteNicki]

@Borda just an idea