Convert doxygen docs (vpp api module and binary api support) to .rst
Added a brief explanation of binary api message numbering for plugins
Change-Id: If7d37f29aa65a884b51f3d27957f80d1357ed29b
Signed-off-by: andrew <andrew.olechtchouk@gmail.com>
Signed-off-by: Dave Barach <dave@barachs.net>
