Docs: rewrite README
Docs: rewrite README

Closes #284.
Part of #248.

[skip ci]

rgrinberg/lwt,rneswold/lwt,ocsigen/lwt,ocsigen/lwt,c-cube/lwt,rneswold/lwt,rgrinberg/lwt,c-cube/lwt,ocsigen/lwt,c-cube/lwt,rgrinberg/lwt,rgrinberg/lwt,rneswold/lwt