mon: fix wrong arg to "instructed to" status message

Fixes: #6293
Signed-off-by: Dan Mick <dan.mick@inktank.com>
Merge pull request #609 from dmick/wip-6293

mon: fix wrong arg to "instructed to" status message

Reviewed-by: David Zafman <david.zafman@inktank.com>