internals: extract frame-based protocol docs to own document...
internals: extract frame-based protocol docs to own document
wireprotocol.txt is quite long and difficult to digest. The
frame-based protocol is effectively a standalone concept (and could
even be used outside of Mercurial). So this commit extracts its
docs to a standalone file.
The first few paragraphs were rewritten as part of the extraction.
Sections headers were adjusted accordingly.
Existing referalls in wireprotocol.txt were updated to refer to the
new doc / concept, which I've started referring to as `hgrpc`.
I'm on the fence as to whether to move the HTTP and SSH transport
details to the new doc as well. For now, I'm leaving them in
wireprotocol.txt.
Differential Revision:
https://phab.mercurial-scm.org/D4443
