NMS-6677: Documentation OmsaStorageMonitor

- Changed name in the example configuration from OMSA_Storage_Disk_1/2 to OMSA-Disk-Array-1/2
- Minor format changes
NMS-6677: Enhancement docu OmsaStorageMonitor

- Clearified behavior for status monitor by reading the source
- Refactoring and added link to the STORAGEMANAGEMENT-MIB