[Feature]: Backend support/docs example

[zmzlois]

What problem does this feature solve?

wondering when will we incorporate backend support since it's a static site

I was thinking to build an interactive roadmap so people can add features on the doc site using Redis + Deno or whatever edge function but not sure will the deploy fail if I add "use server" flag

example like https://roadmap.upstash.com/

What does the proposed API look like?

a section on the doc about backend:

1. using serverless function
2. "use server" whether it is supported (@chenjiahan said it won't) ? I have see express support on github for rspress, but it's not lived on the docs about how mdx + react component + backend will co-live together

Since Rspress doesn't support backend as discussion with @chenjiahan maybe good to include a doc section "How to use module federation to allow a remote module for backend service"

Maybe I can open a PR on this after I finish our current documentation and experiment with how MF works with Rspress?