minor #6650 fix dumper default representation (Jamal Youssefi)

This PR was submitted for the master branch but it was merged into the 2.7 branch instead (closes #6650).

Discussion
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fix dumper default representation

Hi,

The default representation of dumper when using `Yaml` class is expanded:
`public static function dump($array, $inline = 2, $indent = 4, $flags = 0)`

May be i'm wrong because the `$inline` argument is different in `Yaml` (default inline=2 so expanded) and `Dumper` (default inline=0 so inline) class. So it depend to which class we refer to.

Commits
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def7c99 fix dumper default representation

Author: xabbuh

components/yaml/introduction.rst

@@ -167,12 +167,15 @@ Array Expansion and Inlining
 ............................
 
 The YAML format supports two kind of representation for arrays, the expanded
-one, and the inline one. By default, the dumper uses the inline
+one, and the inline one. By default, the dumper uses the expanded
 representation:
 
 .. code-block:: yaml
 
-    { foo: bar, bar: { foo: bar, bar: baz } }
+    foo: bar
+    bar:
+        foo: bar
+        bar: baz
 
 The second argument of the :method:`Symfony\\Component\\Yaml\\Yaml::dump`
 method customizes the level at which the output switches from the expanded