Small fixes to specs
Remove rebar from the guide

The example isn't converted yet but will soon.
Add a manual

This is the manual for what is going to be in 1.0. It includes
two things that are not in the code yet: the shutdown option
and the accept_ack transport callback.
Add an introductory chapter about parsing
Add accept_ack on all transports and ack_timeout transport option

Doing this in the connection process allows us to free acceptors
to start accepting more connections quicker, especially under load.