Change wording cc @michaelklishin

Author: lukebakken

projects/specs/amqp0-9-1.xml

@@ -189,7 +189,7 @@
 
   <constant name = "no-route" value = "312" class = "soft-error">
     <doc>
-      Returned when RabbitMQ sends back with 'basic.return' when a 'mandatory'
+      Returned when RabbitMQ sends 'basic.return' when a 'mandatory'
       message cannot be delivered to any queue.
     </doc>
   </constant>