add a link to new notebook

[sonichi]

          > Would you like to add a link in https://microsoft.github.io/autogen/docs/Examples/AutoGen-AgentChat and https://microsoft.github.io/autogen/docs/Use-Cases/agent_chat#diverse-applications-implemented-with-autogen ? It's OK to do it in a separate PR.

Yes OK. I'll work on this in a separate PR after this PR is merged to avoid dead links.

Originally posted by @joshkyh in #482 (comment)

[joshkyh]

My PR has been merged. Please assign this to me. :)