Mention queueMax=0

Author: cjbj

doc/api.md

@@ -1965,6 +1965,9 @@ The number of milliseconds after which connection requests waiting in
 the connection request queue are terminated.  If `queueTimeout` is
 0, then queued connection requests are never terminated.
 
+If immediate timeout is desired, set related property
+[`queueMax`](#propdbqueuemax) to 0.
+
 The default value is 60000.
 
 This property may be overridden when [creating a connection pool](#createpool).