Add Markdown pre-commit checks

[tatiana]

• Linting
• Codespell (spelling)
• Dead link check

And fixes problems identified by them when running:

pre-commit run --all-files

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.31%. Comparing base (e9f9929) to head (d403a02).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #329   +/-   ##
=======================================
  Coverage   93.31%   93.31%           
=======================================
  Files          10       10           
  Lines         778      778           
=======================================
  Hits          726      726           
  Misses         52       52           

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[pankajkoti]

LGTM, thanks for adding these checks. Also, would like to seek attention on whether we need to restore the mkdocs.yml file that's currently getting removed with this PR.