It's a bit confusing: the "global options" are valid as "global options"
for all client commands (i.e. all but daemon).
Example: `docker --log-level info run`
For `docker daemon`, these "global options" are only valid as "command
options".
Example: `docker daemon --log-level info`
As command completion cannot tell which command the user is going to
type next, completion for the daemon command has to allow illegal
syntaxes like
`docker --log-level info daemon --log-level info`
Signed-off-by: Harald Albers <github@albersweb.de>