DOCS-782 update writeBacksQueued to reflect change from Boolean result

Author: Ed Costello

source/reference/command/writeBacksQueued.txt

@@ -3,11 +3,32 @@ writeBacksQueued (internal)
 ===========================
 
 .. default-domain:: mongodb
-
+  
 .. dbcommand:: writeBacksQueued
 
-   :dbcommand:`writeBacksQueued` is an internal command that returns true if
-   there are operations in the write back queue for the given :program:`mongos`.
-   This command applies to :term:`sharded clusters <sharded cluster>` only.
-
+   :dbcommand:`writeBacksQueued` is an internal command that returns
+   a document reporting there are operations in the write back queue 
+   for the given :program:`mongos` and information about the queues.
+   
+   :field Boolean hasOpsQueued:
+      
+      True if there are writeBack operations queued.
+      
+   :field integer totalOpsQueued:
+   
+      The number of operations queued.
+      
+   :field document queues:
+   
+      A document listing the queues, with fields detailing the size of
+      each queue and the time since the last call.
+      
+      n
+       
+         The size of the queue.
+         
+      minutesSinceLastCall
+      
+         The minutes since the last call.
+         
    .. slave-ok, admin-only