docs:monitor: Fill in fan_missing_error_delay details

The `fan_missing_error_delay` attribute contains the amount of time(in
seconds) to delay logging an error against the fan when its not present.
When this attribute is not given, the default is no error being logged
when the fan is marked as not present.

Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
Change-Id: I52a462e5f339e4404d3523c06695c010cb0de264
1 file changed