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.
Update erlang.mk
Update erlang.mk again
Remove the confusing doc folder

All documentation is in README.md, guide/ and manual/ now.
Add example using gen_server