Fixed broken links.

[afourney]

Why are these changes needed?

Fixed some broken links on the AutoGenBench blogpost that resulted from a last-minute folder renaming.

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-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bcfd770) 32.48% compared to head (fc38be2) 32.48%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1408   +/-   ##
=======================================
  Coverage   32.48%   32.48%           
=======================================
  Files          41       41           
  Lines        4907     4907           
  Branches     1120     1120           
=======================================
  Hits         1594     1594           
  Misses       3187     3187           
  Partials      126      126           

Flag	Coverage Δ
unittests	32.44% <ø> (ø)

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[qingyun-wu]

LGTM!