[release-20.0-rc] Release docs: Add vreplication related entries to the v20 summary (#16259)

[vitess-bot]

Description

This is a backport of #16259

[vitess-bot]

Review Checklist

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[frouioui]

we should duplicate the changes in this file to the release_notes.md file

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.52%. Comparing base (eef7761) to head (e9f7bc0).

Additional details and impacted files

@@                 Coverage Diff                 @@
##           release-20.0-rc   #16270      +/-   ##
===================================================
+ Coverage            68.51%   68.52%   +0.01%     
===================================================
  Files                 1541     1541              
  Lines               197788   197788              
===================================================
+ Hits                135505   135542      +37     
+ Misses               62283    62246      -37     

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[frouioui]

Closing this PR. I directly cherry-picked the changes to #16258.