Documentation improvements

[Lukasa]

Received via email:

• According to this, Hyper-h2 is an HTTP/2 implementation, so does it make sense to say that it's for "writing fully-fledged HTTP/2 implementations".
• At first reading, it's not at all clear to me what you mean by the "top" and "bottom" of an H2Connection objection.
• It seems odd to me that things like "send headers" and "send data" are formatted as code.
• The five points describing the loop sort of make sense -- but I'm not sure whether it describes anything beyond a normal event loop
• Before 3.5, socket.listen() requires a backlog argument, so the code in your example doesn't work
• You should make it clear that the reader should install hyper-h2 alongside installing hyper.
• When you said "But what we didn’t see was hyper making a request, and hyper was clearly hanging, waiting for something. Why?" it's not clear what the relationship is between us not seeing hyper making a request, and hyper hanging.
• I reckon it's worth making it clear right at the top that Hyper-h2 doesn’t do any I/O, and it'd be interesting to talk about why.