Fix warning callout

Author: mribeirodantas

docs/hello_nextflow/07_hello_modules.md

@@ -34,9 +34,11 @@ cd hello-modules
 ```
 
 !!! warning
-If you're continuing on directly from Part 5, you'll need to move up one directory first.
-`     cd ../hello-modules
-    `
+
+    If you're continuing on directly from Part 5, you'll need to move up one directory first.
+    ```
+     cd ../hello-modules
+    ```
 
 The `hello-modules` directory has the same content and structure that you're expected to end up with in `hello-config` on completion of Part 5.