NMS-6641: Documentation CiscoIpSlaMonitor

http://issues.opennms.org/browse/NMS-6641
- Migrated from wiki http://www.opennms.org/wiki/Cisco_IP_SLA_Monitor

Todo Review:
- [x] Typo and grammar
- [ ] Formatting and conventions
- [ ] Content
Can we format this so that the object Ids are lined up correctly? So you could see the differences?