Replace :ref: with :doc:

It seems guides does not render those properly. Anyway, I do not see a
reason to use such a convoluted and error-prone way of building a link.

docs/en/index.rst

@@ -66,7 +66,7 @@ looks like this:
 
 The annotation class is declared as an annotation by ``@Annotation``.
 
-:ref:`Read more about custom annotations. <custom>`
+:doc:`Read more about custom annotations. <custom>`
 
 Reading annotations
 ===================
@@ -103,7 +103,7 @@ Otherwise, :ref:`please take a look to the other annotation autoload mechanisms
 A reader has multiple methods to access the annotations of a class or
 function.
 
-:ref:`Read more about handling annotations. <annotations>`
+:doc:`Read more about handling annotations. <annotations>`
 
 IDE Support
 -----------
@@ -112,6 +112,3 @@ Some IDEs already provide support for annotations:
 
 - Eclipse via the `Symfony2 Plugin <https://github.com/pulse00/Symfony-2-Eclipse-Plugin>`_
 - PhpStorm via the `PHP Annotations Plugin <https://plugins.jetbrains.com/plugin/7320-php-annotations>`_ or the `Symfony Plugin <https://plugins.jetbrains.com/plugin/7219-symfony-support>`_
-
-.. _Read more about handling annotations.: annotations
-.. _Read more about custom annotations.: custom