qga: update guest-suspend-ram and guest-suspend-hybrid descriptions

qga: update guest-suspend-ram and guest-suspend-hybrid descriptions

This patch updates the descriptions of 'guest-suspend-ram' and
'guest-suspend-hybrid' to mention that both commands relies now
on the proper support for wake up from suspend, retrieved by the
'wakeup-suspend-support' attribute of the 'query-current-machine'
QMP command.

Reported-by: Balamuruhan S <[email protected]>
Signed-off-by: Daniel Henrique Barboza <[email protected]>
Reviewed-by: Michael Roth <[email protected]>
Message-Id: <20181205194701[email protected]>
Reviewed-by: Markus Armbruster <[email protected]>
Acked-by: Eduardo Habkost <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>