Fix few doc formatting errors

[SkafteNicki]

What does this PR do?

Fixes some documentation errors. For example look at the parameters section here:
https://torchmetrics.readthedocs.io/en/stable/references/metric.html

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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Make sure you had fun coding 🙃

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📚 Documentation preview 📚: https://torchmetrics--1870.org.readthedocs.build/en/1870/

[codecov]

Codecov Report

Merging #1870 (3a4ab1f) into master (130cb77) will increase coverage by 0%.
The diff coverage is 100%.

❗ Current head 3a4ab1f differs from pull request most recent head 663d92a. Consider uploading reports for the commit 663d92a to get more accurate results

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1870   +/-   ##
======================================
  Coverage      87%     87%           
======================================
  Files         258     258           
  Lines       14591   14592    +1     
======================================
+ Hits        12731   12732    +1     
  Misses       1860    1860