Updated IOPS definition

StoredProcedures/PerformanceCollector.Addin_IO.sql

@@ -21,6 +21,7 @@ BEGIN
 	if datediff (hh,COALESCE(@nowprev,'1/1/1980'),@now) > @PollingInterval   
 	BEGIN	
 		--Disk Latencies and io_stalls
+		--(num_of_reads + num_of_writes/Time since last sample) = IOPS
 		INSERT INTO PerformanceCollector.IOStalls (CurrTime, ServerName, DbName, FileType, num_of_writes, 
 			num_of_reads, num_of_bytes_written, num_of_bytes_read, io_stall_write_ms, io_stall_read_ms, 
 			io_stall, ReadLatency, WriteLatency, Latency, Drive,PhysicalFileName)