Add section to the docs about ecosystem / ASGI integration?

[dantownsend]

I know it's still early days for Xpresso, but how about an ecosystem page in the docs?

I know Piccolo is compatible, and there's bound to be other generic ASGI middleware etc which is known to work.

Just an idea.

[adriangb]

Yup that's a good idea! I'll use this issue as a reminder 😄