minor #6121 [MicroKernel] Fixed the display of a code block (jeremyFreeAgent)

This PR was merged into the 2.8 branch.

Discussion
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[MicroKernel] Fixed the display of a code block

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.8
| Fixed tickets |

The display of a php code block was a quote.

Commits
-------

acbadd2 [MicroKernel] Fixed the display of a code block

Author: wouterj

cookbook/configuration/micro-kernel-trait.rst

@@ -280,7 +280,7 @@ your *kernel* lives in. Since ``AppKernel`` lives in ``app/``, this template liv
 at ``app/Resources/views/micro/random.html.twig``.
 
 Finally, you need a front controller to boot and run the application. Create a
-``web/index.php``:
+``web/index.php``::
 
     // web/index.php