bug #3961 Fixing php coding (mvhirsch)

This PR was merged into the 2.3 branch.

Discussion
----------

Fixing php coding

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | n/a

There is a syntax error in those arrays, so I fixed it.
I also added the configuration-block macro as it seems to be missing on that page.

Commits
-------

68a8ab1 added block macro
f2aad67 fixed small php syntax error

cookbook/templating/namespaced_paths.rst

@@ -91,6 +91,8 @@ the first template that exists, starting from the first configured path. This
 feature can be used as a fallback mechanism to load generic templates when the
 specific template doesn't exist.
 
+.. configuration-block::
+
     .. code-block:: yaml
 
         # app/config/config.yml
@@ -124,7 +126,7 @@ specific template doesn't exist.
                 '%kernel.root_dir%/../vendor/acme/themes/theme1' => 'theme',
                 '%kernel.root_dir%/../vendor/acme/themes/theme2' => 'theme',
                 '%kernel.root_dir%/../vendor/acme/themes/common' => 'theme',
-            );
+            ),
         ));
 
 Now, you can use the same ``@theme`` namespace to refer to any template located