Minor Updates to AGS Docs

[victordibia]

Why are these changes needed?

Minor Updates to AGS Docs
Add link to usage section of docs in readme

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.61%. Comparing base (115fefa) to head (b27e1c4).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5010   +/-   ##
=======================================
  Coverage   68.61%   68.61%           
=======================================
  Files         156      156           
  Lines       10053    10053           
=======================================
  Hits         6898     6898           
  Misses       3155     3155           

Flag	Coverage Δ
unittests	68.61% <ø> (ø)

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