Update incremental adoption in rewrites doc (#24186)
Update incremental adoption in rewrites doc (#24186)

This updates the incremental adoption section in the rewrites docs to mention the new fallback rewrites instead of the no-op rewrite and also points to the incrementally adopting Next.js doc. 

## Documentation / Examples

- [x] Make sure the linting passes

Closes: https://github.com/vercel/next.js/pull/23700
Closes: https://github.com/vercel/next.js/issues/23699
flybayer/next.js,flybayer/next.js,zeit/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,zeit/next.js,flybayer/next.js,azukaru/next.js,azukaru/next.js,zeit/next.js,flybayer/next.js