Merge pull request #2113 from tarjei/docs-patch-1

Clean up variable naming to make docs a bit clearer

docs/testing.rst

@@ -37,8 +37,8 @@ a response or exception by shifting return values off of a queue.
         new RequestException("Error Communicating with Server", new Request('GET', 'test'))
     ]);
 
-    $handler = HandlerStack::create($mock);
-    $client = new Client(['handler' => $handler]);
+    $handlerStack = HandlerStack::create($mock);
+    $client = new Client(['handler' => $handlerStack]);
 
     // The first request is intercepted with the first response.
     echo $client->request('GET', '/')->getStatusCode();
@@ -68,11 +68,13 @@ history of the requests that were sent by a client.
     $container = [];
     $history = Middleware::history($container);
 
-    $stack = HandlerStack::create();
+    $handlerStack = HandlerStack::create(); 
+    // or $handlerStack = HandlerStack::create($mock); if using the Mock handler.
+    
     // Add the history middleware to the handler stack.
-    $stack->push($history);
+    $handlerStack->push($history);
 
-    $client = new Client(['handler' => $stack]);
+    $client = new Client(['handler' => $handlerStack]);
 
     $client->request('GET', 'http://httpbin.org/get');
     $client->request('HEAD', 'http://httpbin.org/get');