Add LM Studio Example in Topics

[ekzhu]

Why are these changes needed?

Adding an example for using LM Studio's multi model serving feature.

Related issue number

#1994

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-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.74%. Comparing base (ca506ba) to head (cca2376).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2044      +/-   ##
==========================================
- Coverage   36.79%   36.74%   -0.06%     
==========================================
  Files          66       66              
  Lines        7060     7060              
  Branches     1541     1541              
==========================================
- Hits         2598     2594       -4     
- Misses       4234     4237       +3     
- Partials      228      229       +1     

Flag	Coverage Δ
unittests	36.74% <ø> (-0.06%)	⬇️

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