[#2151] Reorganizing part of the monolog cookbook to put usage first

cookbook/logging/monolog.rst

@@ -10,14 +10,34 @@ inspired by the Python LogBook library.
 Usage
 -----
 
-In Monolog each logger defines a logging channel. Each channel has a
-stack of handlers to write the logs (the handlers can be shared).
+To log a message simply get the logger service from the container in
+your controller::
+
+    public function indexAction()
+    {
+        $logger = $this->get('logger');
+        $logger->info('I just got the logger');
+        $logger->err('An error occurred');
+
+        // ...
+    }
+
+The ``logger`` service has different methods for different the logging levels.
+See :class:`Symfony\\Component\\HttpKernel\\Log\\LoggerInterface` for details
+on which methods are available.
+
+Handlers and Channels: Writing logs to different Locations
+----------------------------------------------------------
+
+In Monolog each logger defines a logging channel, which organizes your log
+messages into different "categories". Then, each channel has a stack of handlers
+to write the logs (the handlers can be shared).
 
 .. tip::
 
     When injecting the logger in a service you can
-    :ref:`use a custom channel<dic_tags-monolog>` to see easily which
-    part of the application logged the message.
+    :ref:`use a custom channel<dic_tags-monolog>` control which "channel"
+    the logger will log to.
 
 The basic handler is the ``StreamHandler`` which writes logs in a stream
 (by default in the ``app/logs/prod.log`` in the prod environment and
@@ -29,19 +49,6 @@ messages in a buffer and to log them only if a message reaches the
 action level (ERROR in the configuration provided in the standard
 edition) by forwarding the messages to another handler.
 
-To log a message simply get the logger service from the container in
-your controller::
-
-    $logger = $this->get('logger');
-    $logger->info('I just got the logger');
-    $logger->err('An error occurred');
-
-.. tip::
-
-    Using only the methods of the
-    :class:`Symfony\\Component\\HttpKernel\\Log\\LoggerInterface` interface
-    allows to change the logger implementation without changing your code.
-
 Using several handlers
 ~~~~~~~~~~~~~~~~~~~~~~