Make General SubAgent not hidden

[dbpolito]

I find general agent very useful and i use it a lot of time to trigger parallel tasks, with prompts like: do each task in a separate @general when working on big projects, even it's hidden it works.

But i think maybe exposing and maybe adding better docs might help people leverage more on it?

TBH i don't see any reason to general be hidden.

Another argument is that @general is mentioned in the docs: https://opencode.ai/docs/agents/#usage