Improve openbmctool_execute_command documentation
Improve openbmctool_execute_command documentation

Change-Id: I56ed1897288bf549bd5b288b9a10b4b7d6d084a1
Signed-off-by: Michael Walsh <10404802c7de463f402c4a18638106ca1b12ef61@us.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation