nonvolatile memory express metrics added

Author: Shalini-IBM

docs/lssystemstats_metrics.md

@@ -147,4 +147,12 @@
 
 # HELP spectrum_systemStats_write_cache_pc The percentage of the write cache usage for the node.
 # TYPE spectrum_systemStats_write_cache_pc gauge
+# HELP spectrum_systemStats_nvme_rdma_mb The total number of megabytes transferred per second (MBps) for NVMe over RDMA traffic on the system.
+# TYPE spectrum_systemStats_nvme_rdma_mb gauge
+# HELP spectrum_systemStats_nvme_rdma_io The total I/O operations that are transferred per second for NVMe over RDMA traffic on the system.
+# TYPE spectrum_systemStats_nvme_rdma_io gauge
+# HELP spectrum_systemStats_nvme_tcp_mb The total number of megabytes transferred per second (MBps) for NVMe over TCP traffic on the system.
+# TYPE spectrum_systemStats_nvme_tcp_mb gauge
+# HELP spectrum_systemStats_nvme_tcp_io The total I/O operations that are transferred per second for NVMe over TCP traffic on the system.
+# TYPE spectrum_systemStats_nvme_tcp_io gauge
 ```