minor #3933 render directory inside a code block (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

render directory inside a code block

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | #3932

Commits
-------

6386f9c render directory inside a code block

Author: weaverryan

contributing/documentation/standards.rst

@@ -92,6 +92,8 @@ Files and Directories
 * When you list a Symfony file/directory hierarchy, use ``your-project/`` as the
   top level directory. E.g.
 
+  .. code-block:: text
+
       your-project/
       ├─ app/
       ├─ src/