doc: Set book edition number to the "1"

"1" sounds better when we mention about the "first" edition or say the
"publishing" edition.

If needed, we might want to increase the edition numbers automatically later,
for instance based on the micro version of the protocol or something like
that.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>