Update sync_docs.yaml

[a-velasco]

A new sync_docs.yaml workflow was released in data-platform-workflows v19.2.0. It overwrites the old experimental _sync_docs.yaml workflow and releases it to the public interface.

This PR:

• Corrects the filename to match the new syntax without the experimental _ prefix.
• Removes the now unnecessary Discourse API credentials
• Adds automatic reviewers

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.89%. Comparing base (64b94d2) to head (a008e81).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #588   +/-   ##
=======================================
  Coverage   70.89%   70.89%           
=======================================
  Files          12       12           
  Lines        3030     3030           
  Branches      536      536           
=======================================
  Hits         2148     2148           
  Misses        768      768           
  Partials      114      114           

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