Update github/microsoft/autogen links

[kartikx]

Why are these changes needed?

Two links in the LLM Configuration documentation are broken because they are pointing to the Microsoft repo. I updated these links to point to ag2ai instead.

Related issue number

Checks

• I've included any doc changes needed for https://ag2ai.github.io/ag2/. See https://ag2ai.github.io/ag2/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.

[qingyun-wu]

@kartikx, good catch! Thanks for the fix!

[qingyun-wu]

LGTM!