Merge branch 'issue-19-password-monitoring' into 'master'

Add list of nagios checks to Passwords application monitoring section.

See merge request !93

docs/services/passwords.md

@@ -91,6 +91,11 @@ Deployed by installing RPMs from the [Bes repo](https://wiki.cam.ac.uk/ucs/Bes_-
 The Password app is monitored by the UIS infra-sas
 [nagios service](https://nagios.uis.cam.ac.uk/nagios/).
 
+Sevices currently monitored:
+* ping - standard nagios ping check.
+* SSL - checks for a valid SSL certificate.
+* devgroup - checks for a 200 response from the /adm/status page.
+* disc-space - checks for at least 15% free disk space.
 ### Debugging
 
 The Password app cannot be run locally, and therefore the test instance should