Tutorial Chapter for SelectorGroupChat

[ekzhu]

1. Basic usage
2. Termination condition based on text mention such as "APPROVE"
3. Customized speaker selection function, make a reference to StateFlow in v0.2.

Follow this example in Core documentation: https://microsoft.github.io/autogen/dev/user-guide/core-user-guide/design-patterns/group-chat.html

Or, alternatively, a literature review usage case https://microsoft.github.io/autogen/dev/user-guide/agentchat-user-guide/examples/literature-review.html

For either example, use mocked tools rather than actual implementation. The goal is to demonstrate the usage of the API not the actual scenario.

Introduce custom speaker selection after introducing the basic usage of the API.