input: move input-send-event into experimental namespace

Ongoing discussions on how we are going to specify the console,
so tag the command as experiental so we can refine things in
the 2.3 development cycle.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1416923657-10614-1-git-send-email-armbru@redhat.com
[Spell out "not a stable API", and x- the QAPI schema, too]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Update version for v2.2.0-rc3 release

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>