Shovels: document delete-after & no-ack incompatibility

Remove src-delete-after:queue-length option for amqp10. It was never supported

Author: dcorbacho

docs/shovel-dynamic.md

@@ -588,7 +588,8 @@ the declaration process.
         </div>
         <div>
           If set to an integer, then the shovel will transfer that
-          number of messages before deleting itself.
+          number of messages before deleting itself. This option cannot
+          be used in conjunction with <code>ack-mode : no-ack</code>.
         </div>
       </td>
     </tr>
@@ -838,15 +839,10 @@ counterparts.
           The default is <code>never</code>, meaning the
           shovel should never delete itself.
         </div>
-        <div>
-          If set to <code>queue-length</code> then the shovel will
-          measure the length of the source queue when starting up,
-          and delete itself after it has transferred that many
-          messages.
-        </div>
         <div>
           If set to an integer, then the shovel will transfer that
-          number of messages before deleting itself.
+          number of messages before deleting itself. This option cannot
+          be used in conjunction with <code>ack-mode : no-ack</code>.
         </div>
       </td>
     </tr>
@@ -922,7 +918,8 @@ the declaration process.
         </div>
         <div>
           If set to an integer, then the shovel will transfer that
-          number of messages before deleting itself.
+          number of messages before deleting itself. This option cannot
+          be used in conjunction with <code>ack-mode : no-ack</code>.
         </div>
       </td>
     </tr>