Follow up to event documentation updates

[sm-msft]

Description

• Address review feedback from pull request Add QUIC stream event documentation and other event related doc updates #4960
• Add missing events/event payload descriptions
• Add a doc for preview features

Fixes #1795

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.08%. Comparing base (fbf1e29) to head (0eb377b).
Report is 39 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4969      +/-   ##
==========================================
+ Coverage   86.60%   87.08%   +0.47%     
==========================================
  Files          57       59       +2     
  Lines       17982    18011      +29     
==========================================
+ Hits        15573    15684     +111     
+ Misses       2409     2327      -82     

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[Copilot]

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.