CompatHelper: bump compat for Documenter to 1 for package docs, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the Documenter package from 0.27 to 0.27, 1 for package docs.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.01%. Comparing base (9da044c) to head (7edcc72).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #181      +/-   ##
==========================================
- Coverage   95.30%   95.01%   -0.29%     
==========================================
  Files          14       15       +1     
  Lines         681      682       +1     
==========================================
- Hits          649      648       -1     
- Misses         32       34       +2     

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