Merge branch 'content_rules' into 'preview'

Turn code block into example

See merge request !1062

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

@@ -7,7 +7,7 @@
 ## Motivation and Rationale
 
 This page holds rules regarding the layout, content, and writing of this
-documentation. The goals are to provide a comprehensive, consistent, up-to-date and well-written
+documentation. The goals are to provide a comprehensive, consistent and well-written
 documentation that is pure joy to read and use. It shall help to find answers and provide knowledge
 instead of being the bottleneck and a great annoyance. Therefore, we set up some rules which
 are outlined in the following.
@@ -330,7 +330,7 @@ placeholders. In particular, use the generic placeholders depicted in the follow
 The table also holds a second placeholder, if, e.g., you need a second login to formulate an example.
 
 | Description | Placeholder | 2nd Placeholder |
-|---|---|
+|---|---|---|
 | Username | Marie | Martin |
 | Login | `marie` | `martin` |
 | E-mail | marie@tu-dresden.de | martin@tu-dresden.de |
@@ -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"