doc: fix testpmd commands for TM capabilities

doc: fix testpmd commands for TM capabilities

Command used for querying node or level capabilities requires
argument which specifies which set of capabilities to show.

Thus trying to show node/level capabilities using current
documentation will not work. Fix that by adding missing
arguments to command documentation.

Fixes: 5b590fbe09b6 ("app/testpmd: add traffic management forwarding mode")
Cc: stable@dpdk.org
Signed-off-by: Tomasz Duszynski <tdu@semihalf.com>
Acked-by: Jasvinder Singh <jasvinder.singh@intel.com>