Add usage examples to README

[mfelsche]

Give a simple example for:

• starting a server
• handling requests
• building responses

also link to the examples.

[erf]

Hi, maybe you could add some notes in a document regarding benchmarks / performance. Maybe compare with previous http server or other frameworks.

[mfelsche]

Yes, good point @erf !
I first wanted to set up a good real-world setting on gcp for getting some more meaningful numbers than stuff running on my local machine, but got stuck with other stuff. I will pick this up soonish.