minor #4357 fix Twig-extensions links (mhor)

This PR was merged into the 2.3 branch.

Discussion
----------

fix Twig-extensions links

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

related twigphp/Twig#1554, twigphp/Twig-extensions#123

Commits
-------

82ea9df fix Twig-extensions links

Author: wouterj

cookbook/templating/twig_extension.rst

@@ -126,7 +126,7 @@ Learning further
 For a more in-depth look into Twig Extensions, please take a look at the
 `Twig extensions documentation`_.
 
-.. _`Twig official extension repository`: https://github.com/fabpot/Twig-extensions
+.. _`Twig official extension repository`: https://github.com/twigphp/Twig-extensions
 .. _`Twig extensions documentation`: http://twig.sensiolabs.org/doc/advanced.html#creating-an-extension
 .. _`global variables`: http://twig.sensiolabs.org/doc/advanced.html#id1
 .. _`functions`: http://twig.sensiolabs.org/doc/advanced.html#id2

reference/dic_tags.rst

@@ -1393,6 +1393,6 @@ Then, tag it with the ``validator.initializer`` tag (it has no options).
 For an example, see the ``EntityInitializer`` class inside the Doctrine Bridge.
 
 .. _`Twig's documentation`: http://twig.sensiolabs.org/doc/advanced.html#creating-an-extension
-.. _`Twig official extension repository`: https://github.com/fabpot/Twig-extensions
+.. _`Twig official extension repository`: https://github.com/twigphp/Twig-extensions
 .. _`SwiftMailer's Plugin Documentation`: http://swiftmailer.org/docs/plugins.html
 .. _`Twig Loader`: http://twig.sensiolabs.org/doc/api.html#loaders