docs: add h3 middleware example

[oritwoen]

I was a bit surprised that the only example of middleware is express, especially that in the unjs ecosystem there is a super h3.

I recently created my own CDN so I am also adding information for others.

[codecov]

Codecov Report

Merging #144 (881581e) into main (9ed2708) will not change coverage.
The diff coverage is n/a.

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  Misses        410      410           

[pi0]

Thanks for the PR dear @oritwoen and sorry took long to review.

IPX was made before H3 and therefore middleware format is express friendly. I am going to work on v2 with h3-first API support but in the meantime, added little updates to your examples to merged it to main docs 👍🏼