feature #6583 Adding a description for the use_microseconds parameter…

… introduced in MonologBundle v2.11 (jorgelbg)

This PR was squashed before being merged into the 2.3 branch (closes #6583).

Discussion
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Adding a description for the use_microseconds parameter introduced in MonologBundle v2.11

This adds a small paragraph bellow the usage section with an explanation and an example block.

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | >= 2.3
| Fixed tickets | #6466

Commits
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4c5d42f Adding a description for the use_microseconds parameter introduced in MonologBundle v2.11

cookbook/logging/monolog.rst

@@ -289,6 +289,67 @@ option of your handler to ``rotating_file``:
             ),
         ));
 
+How to Disable Microseconds Precision
+-------------------------------------
+
+.. versionadded:: 2.11
+    The ``use_microseconds`` option was introduced in MonologBundle 2.11.
+
+Setting the parameter ``use_microseconds`` to ``false`` forces the logger to reduce
+the precision in the ``datetime`` field of the log messages from microsecond to second,
+avoiding a call to the ``microtime(true)`` function and the subsequent parsing.
+Disabling the use of microseconds can provide a small performance gain speeding up the
+log generation. This is recommended for systems that generate a large number of log events.
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # app/config/config.yml
+        monolog:
+            use_microseconds: false
+            handlers:
+                applog:
+                    type: stream
+                    path: /var/log/symfony.log
+                    level: error
+
+    .. code-block:: xml
+
+        <!-- app/config/config.xml -->
+        <?xml version="1.0" encoding="UTF-8" ?>
+        <container xmlns="http://symfony.com/schema/dic/services"
+            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+            xmlns:monolog="http://symfony.com/schema/dic/monolog"
+            xsi:schemaLocation="http://symfony.com/schema/dic/services
+                http://symfony.com/schema/dic/services/services-1.0.xsd
+                http://symfony.com/schema/dic/monolog
+                http://symfony.com/schema/dic/monolog/monolog-1.0.xsd">
+
+            <monolog:config use_microseconds="false">
+                <monolog:handler
+                    name="applog"
+                    type="stream"
+                    path="/var/log/symfony.log"
+                    level="error"
+                />
+            </monolog:config>
+        </container>
+
+    .. code-block:: php
+
+        // app/config/config.php
+        $container->loadFromExtension('monolog', array(
+            'use_microseconds' => false,
+            'handlers' => array(
+                'applog' => array(
+                    'type'  => 'stream',
+                    'path'  => '/var/log/symfony.log',
+                    'level' => 'error',
+                ),
+            ),
+        ));
+
 Adding some extra Data in the Log Messages
 ------------------------------------------