[Python] Mention other model clients in M1 documentation and create inter-references to help navigation

[ekzhu]

We need to mention what are the alternative clients and model providers are compatible with M1 on the following pages:

• https://microsoft.github.io/autogen/stable/user-guide/agentchat-user-guide/magentic-one.html
• https://microsoft.github.io/autogen/stable/reference/python/autogen_ext.teams.magentic_one.html -- it needs to have a reference pointing to the guide page
• https://github.com/microsoft/autogen/tree/main/python/packages/autogen-magentic-one

Consider for the README.md file we remove the code samples and just point to the other pages.

Related issue #5349