enclose YAML strings containing % with quotes

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | #4029

Thanks @iamdto, did you spot some other occurences in the docs?
In this file the issue is not about YAML but more about the first JSON example (see the rendered version on the site). In fact in this part we're talking about the output of the command above, so I think we should let it be a text code block.