Turn code block into example with desc.

doc.zih.tu-dresden.de/docs/contrib/content_rules.md

@@ -338,12 +338,17 @@ The table also holds a second placeholder, if, e.g., you need a second login to
 | Workspace title | `number_crunch` | `long_computations` |
 {: summary="Generic placeholders", align="bottom"}
 
-```console
-marie@login$ ls -l
-drwxr-xr-x   3 marie p_number_crunch      4096 Jan 24  2020 code
-drwxr-xr-x   3 marie p_number_crunch      4096 Feb 12  2020 data
--rw-rw----   1 marie p_number_crunch      4096 Jan 24  2020 readme.md
-```
+!!! example "Output of `ls` command"
+
+   The following code listing depicts the usage of the generic user names and projects as well as
+    recognizable placeholders for files and directory names.
+
+    ```console
+    marie@login$ ls -l
+    drwxr-xr-x   3 marie p_number_crunch      4096 Jan 24  2020 code
+    drwxr-xr-x   3 marie p_number_crunch      4096 Feb 12  2020 data
+    -rw-rw----   1 marie p_number_crunch      4096 Jan 24  2020 readme.md
+    ```
 
 !!! info "Marie"