[Docs]: Remove old swarm notebooks

[marklysze]

Is your feature request related to a problem? Please describe.

The notebooks section contains swarm examples that don't work any more. Please hide them.

The only one I would consider converting to the new group chat is: https://docs.ag2.ai/latest/docs/use-cases/notebooks/notebooks/agentchat_swarm_enhanced/#demonstration

Describe the solution you'd like

No response

Additional context

No response

[marklysze]

CC @harishmohanraj CC @sonichi

[Lancetnik]

CC @sonichi can you review this notebook and remove it if it doesn't work, please?