The introduction calls out the HTTP/1 message format
as problematic; arguably, connection management was
the bigger reason for HTTP/2. Subsequent paragraphs
seem to support this view.
Rewrite para on advantages of compression.
Specify where "support for HTTP/2" is scoped to.

In the current text, it's not clear where the client
is looking for support; a naive reading might be that
they should look for origin support. In fact, it's
next-hop, if we're using Upgrade.
"The" -> "Such an"
makes -> does so by making
Remove superfluous "identifying HTTP/2"
Rework prior knowledge text about connection preface
SETTINGS frame after the preface deserves a MUST
Move case-folding of headers out of section that's specific to pseudo-header fields.
Move TE exception up.
Take slightly awkward sentence out of CompressCookie
Refactor how connection preface is required
Limiting use of 'SETTINGS parameters'