Fix policy command flags order online help and partially doc

[fedepell]

The online help (and partially, just for one command, also the documentation) states that the FLAGS passed to the policy command should be passed after the subcommand, but that actually fails, ie.:

./mc policy list --no-color minio/foobar
Name:
mc policy - manage anonymous access to buckets and objects

USAGE:
mc policy set [FLAGS] PERMISSION TARGET
mc policy set-json [FLAGS] FILE TARGET
mc policy get [FLAGS] TARGET
mc policy get-json [FLAGS] TARGET
mc policy list [FLAGS] TARGET

While passing the flags before the subcommand works correctly:

./mc policy --no-color list minio/foobar
foobar/* => readwrite

This PR fixes the help message and documentation (just for list, for the others was already correct) to indicate the correct syntax.