[#2064] Adding a link from event dispatcher to HttpKernel per @wouterj's suggestion

Author: weaverryan

components/event_dispatcher/introduction.rst

@@ -24,7 +24,7 @@ The Symfony2 Event Dispatcher component implements the `Observer`_ pattern in
 a simple and effective way to make all these things possible and to make your
 projects truly extensible.
 
-Take a simple example from the `Symfony2 HttpKernel component`_. Once a
+Take a simple example from the :doc:`/components/http_kernel/introduction`. Once a
 ``Response`` object has been created, it may be useful to allow other elements
 in the system to modify it (e.g. add some cache headers) before it's actually
 used. To make this possible, the Symfony2 kernel throws an event -
@@ -487,7 +487,6 @@ Now, any listeners to ``store.order`` that have not yet been called will *not*
 be called.
 
 .. _Observer: http://en.wikipedia.org/wiki/Observer_pattern
-.. _`Symfony2 HttpKernel component`: https://github.com/symfony/HttpKernel
 .. _Closures: http://php.net/manual/en/functions.anonymous.php
 .. _PHP callable: http://www.php.net/manual/en/language.pseudo-types.php#language.types.callback
 .. _Packagist: https://packagist.org/packages/symfony/event-dispatcher