Add namespace documentation URL.

Signed-off-by: Kershaw Mehta <[email protected]>

config-zos.md

@@ -15,6 +15,7 @@ The following filesystems SHOULD be made available in each container's filesyste
 
 A namespace wraps a global system resource in an abstraction that makes it appear to the processes within the namespace that they have their own isolated instance of the global resource.
 Changes to the global resource are visible to other processes that are members of the namespace, but are invisible to other processes.
+For more information, see https://www.ibm.com/docs/zos/latest?topic=planning-namespaces-zos-unix.
 
 Namespaces are specified as an array of entries inside the `namespaces` root field.
 The following parameters can be specified to set up namespaces: