Documentation: Fix all broken links

[Javagedes]

MkDocs v1.5.0 Updated how links were evaluated (See "Expanded Validaton of links" section). Before 1.5.0, most links in our documentation were left "untouched" as they either started or ended with a /.

... links that started with / ("absolute") and links that ended with / were left as is ...

However these links are now properly evaluated, which broke most links in edk2-pytool-extensions documentation. With this new evaluation, All of our links that started absolute (/) were now linking relative to tianocore.org instead of tianocore.org/edk2-pytool-library.

This pull request updates the documentation to utilize the newly introduced absolute_links validation setting to be relative_to_docs which updates absolute paths to be relative to tianocore.org/edk2-pytool-extensions and updates any path references to point to the markdown file, which is necessary for the relative_to_docs setting to work as expected.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.31%. Comparing base (ce85203) to head (79b22f7).
Report is 86 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #609      +/-   ##
==========================================
- Coverage   81.43%   81.31%   -0.13%     
==========================================
  Files          56       45      -11     
  Lines        7514     7486      -28     
==========================================
- Hits         6119     6087      -32     
- Misses       1395     1399       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.