Add external link to Shared Kernel wiki

Author: yceruto

configuration/multiple_kernels.rst

@@ -37,7 +37,7 @@ The following example shows how to create a new application for the API of a new
 Step 1) Create a new Application
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-In this example, we will use the Shared Kernel pattern, where, although all applications maintain an isolated context,
+In this example, we will use the `Shared Kernel`_ pattern, where, although all applications maintain an isolated context,
 they can share common bundles, configurations, and code if desired. The optimal approach will depend on your specific
 needs and requirements, so it's up to you to decide which best suits your project.
 
@@ -385,3 +385,5 @@ configuration and permissions. To do that, you will have to repeat the step 1 on
     │     └─ ...
 
 Additionally, you might need to update your web server configuration to set the ``APP_ID=admin`` under a different domain.
+
+.. _`Shared Kernel`: http://ddd.fed.wiki.org/view/shared-kernel