minor #5822 Fixed a syntax issue (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #5822).

Discussion
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Fixed a syntax issue

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.7+
| Fixed tickets | -

Hopefully this will solve the following issue:

![syntax_issue](https://cloud.githubusercontent.com/assets/73419/10634650/a1a33416-77f3-11e5-99b8-8bd5941190bc.png)

Commits
-------

f15a99a Fixed a syntax issue

components/http_foundation/introduction.rst

@@ -255,8 +255,8 @@ by using the following methods:
 :method:`Symfony\\Component\\HttpFoundation\\Request::getEncodings`
     Returns the list of accepted encodings ordered by descending quality.
 
-  .. versionadded:: 2.4
-      The ``getEncodings()`` method was introduced in Symfony 2.4.
+    .. versionadded:: 2.4
+        The ``getEncodings()`` method was introduced in Symfony 2.4.
 
 If you need to get full access to parsed data from ``Accept``, ``Accept-Language``,
 ``Accept-Charset`` or ``Accept-Encoding``, you can use