clarified that endpoints can send frames of any type in the half closed (remote) state
Fleshed out examples of state transitions for the lifetime of a stream for a request/response pair and for the lifetime of a stream for a server push. Also added reference to the states description section to these examples.
tried to clarify slightly confusing language wrt PUSH_PROMISE
Centered the stream states figure (it was driving me crazy!).
Correcting whitespace, tweaking grammar.