Docs: Add code-block wrappers to code examples: testing_documentation.rst (#78966)

* Docs: Add code-block wrappers to code examples: testing_documentation.rst
List of changed files:
- docs/docsite/rst/dev_guide/testing_documentation.rst
* Fix: match whitespace convention of other occurences

docs/docsite/rst/dev_guide/testing_documentation.rst

@@ -31,6 +31,8 @@ To ensure that your module documentation matches your ``argument_spec``:
 
       pip install --user -r test/lib/ansible_test/_data/requirements/sanity.txt
 
-#. run the ``validate-modules`` test::
+#. run the ``validate-modules`` test:
+
+   .. code-block:: bash
 
     ansible-test sanity --test validate-modules mymodule