Some users have been incurring into problems adding new monitors while
following these steps. Some of these problems are due to the meaning of
'{path}' being a bit ambiguous. This patch removes said ambiguity by
replacing '{path}' with '{tmp}', supposed to be a temporary directory
containing the files necessary to add the monitor (monmap and keyring).
Fixes: #3438#3463
Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>