Document using alternative `http` modules

[sc0ttj]

Judging by various benchmarks, and given the reputable code stolen/borrowed to make router, and that it's used inside the node http module, it should already be pretty damn fast - compared to express.js and others.

However, router could be made faster:

Use it inside these http modules, instead of standard NodeJS http module:

• sifrr-server - fastest NodeJS http module
• nanoexpress/nanoexpress - 2nd fastest
• jkyberneees/low-http-server - also faster than built-in http module
• mafintosh/turbo-http - very fast too