NMS-6642: Documentation CiscoPingMibMonitor

JIRA: http://issues.opennms.org/browse/NMS-6642
- Migrated from wiki http://www.opennms.org/wiki/CiscoPingMibMonitor

Todo Review:
- [ ] Typo and grammar
- [ ] Formatting and conventions
- [ ] Content
It is mentioned above that timeout and retry parameters are not read/processed at all.
Shouldn't this be described here as well in addition with a reference to package-retry and packet-count, package-delay and packet-timeout?