Merge pull request #373 from kaushika-msft/patch-1

Append to documentation regarding what BROKER_RECEIVE_WAITFOR means

Author: v-shils

docs/relational-databases/system-dynamic-management-views/sys-dm-os-wait-stats-transact-sql.md

@@ -126,7 +126,7 @@ This command resets all counters to 0.
 |BROKER_FORWARDER |TBD <br /> **Applies to**: [!INCLUDE[ssSQL12](../../includes/sssql11-md.md)] through [!INCLUDE[ssCurrent](../../includes/sscurrent-md.md)].| 
 |BROKER_INIT |Occurs when initializing Service Broker in each active database. This should occur infrequently.| 
 |BROKER_MASTERSTART |Occurs when a task is waiting for the primary event handler of the Service Broker to start. This should occur very briefly.| 
-|BROKER_RECEIVE_WAITFOR |Occurs when the RECEIVE WAITFOR is waiting. This is typical if no messages are ready to be received.| 
+|BROKER_RECEIVE_WAITFOR |Occurs when the RECEIVE WAITFOR is waiting. This may mean that either no messages are ready to be received in the queue or a lock contention is preventing it from receiving messages from the queue.| 
 |BROKER_REGISTERALLENDPOINTS |Occurs during the initialization of a Service Broker connection endpoint. This should occur very briefly.| 
 |BROKER_SERVICE |Occurs when the Service Broker destination list that is associated with a target service is updated or re-prioritized.| 
 |BROKER_SHUTDOWN |Occurs when there is a planned shutdown of Service Broker. This should occur very briefly, if at all.|