HTTP API: document disable_stats and enable_queue_totals

Using GET /api/queues?disable_stats=true&enable_queue_totals=true is far more efficient than the standard GET /api/queues and in many cases will suffice for monitoring and operating purposes.

Author: dcorbacho

deps/rabbitmq_management/priv/www/api/index.html

@@ -56,6 +56,13 @@ <h2>Introduction</h2>
     with the <code>columns</code> parameter. This is a comma-separated
     list of subfields separated by dots. See the example below.</p>
 
+    <p> It is possible to disable the statistics in the GET requests
+      and obtain just the basic information of every object. This reduces
+      considerably the amount of data returned and the memory and resource
+      consumption of each query in the system. For some monitoring and operation
+      purposes, these queries are more appropiate. The query string parameter
+    <code>disable_stats</code> set to <code>true</code> will achieve this.</p>
+
     <p>Most of the GET queries return many fields per
     object. The second part of this guide covers those.</p>
 
@@ -478,7 +485,10 @@ <h2>Reference</h2>
         <td></td>
         <td></td>
         <td class="path">/api/queues</td>
-        <td>A list of all queues. Use <a href="#pagination">pagination parameters</a> to filter queues.</td>
+        <td>A list of all queues. Use <a href="#pagination">pagination parameters</a> to filter queues.
+          The parameter <code>enable_queue_totals</code> can be used in combination with the
+          <code>disable_stats</code> parameter to return a reduced set of fields.
+        </td>
       </tr>
       <tr>
         <td>X</td>
@@ -2158,6 +2168,85 @@ <h2>/api/exchanges/(vhost)/(name)</h2>
     </table>
 
     <h2>/api/queues</h2>
+
+    When using the query parameters combination of <code>disable_stats</code> and
+    <code>enable_queue_totals</code> this query returns the following fields:
+
+    <table>
+      <tr>
+        <td><code>name</code></td>
+        <td>
+          The name of the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>vhost</code></td>
+        <td>
+          The name of the virtual host.
+        </td>
+      </tr>
+      <tr>
+        <td><code>type</code></td>
+        <td>
+          The type of the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>node</code></td>
+        <td>
+          Depending on the type of the queue, this is the node which holds the queue or hosts the leader.
+        </td>
+      </tr>
+      <tr>
+        <td><code>state</code></td>
+        <td>
+          The status of the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>arguments</code></td>
+        <td>
+          The arguments of the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>auto_delete</code></td>
+        <td>
+          The value of the <code>auto_delete</code> argument.
+        </td>
+      </tr>
+      <tr>
+        <td><code>durable</code></td>
+        <td>
+          The value of the <code>durable</code> argument.
+        </td>
+      </tr>
+      <tr>
+        <td><code>exclusive</code></td>
+        <td>
+          The value of the <code>exclusive</code> argument.
+        </td>
+      </tr>
+      <tr>
+        <td><code>messages</code></td>
+        <td>
+          The total number of messages in the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>messages_ready</code></td>
+        <td>
+          The number of messages ready to be delivered in the queue.
+        </td>
+      </tr>
+      <tr>
+        <td><code>messages_unacknowledged</code></td>
+        <td>
+          The number of messages waiting for acknowledgement in the queue.
+        </td>
+      </tr>
+    </table>
+
     <h2>/api/queues/(vhost)</h2>
 
     <p>