feature #6091 Added an example for info() method (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
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Added an example for info() method

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | all
| Fixed tickets | -

This PR just rebases the work made by @OskarStark in #5632.

Commits
-------

f966c0f Fixed another typo
26a8d1f Fixed a typo
9922273 Added an example for info() method

components/config/definition.rst

@@ -425,9 +425,34 @@ All options can be documented using the
 :method:`Symfony\\Component\\Config\\Definition\\Builder\\NodeDefinition::info`
 method.
 
+.. code-block:: php
+
+    $rootNode
+        ->children()
+            ->integerNode('entries_per_page')
+                ->info('This value is only used for the search results page.')
+                ->defaultValue(25)
+            ->end()
+        ->end()
+    ;
+
 The info will be printed as a comment when dumping the configuration tree
 with the ``config:dump-reference`` command.
 
+In YAML you may have:
+
+.. code-block:: yaml
+
+    # This value is only used for the search results page.
+    entries_per_page:     25
+
+and in XML:
+
+.. code-block:: xml
+
+    <!-- entries-per-page: This value is only used for the search results page. -->
+    <config entries-per-page="25" />
+
 Optional Sections
 -----------------