Answer by Nisse Engström for What to do when a tiny edit would markedly improve the post?

In this particular case, I would change the list markers from 3) to 3.. This will cause the text to be marked up as a proper HTML list.

If you then prefix the code block with eight spaces, it will be contained inside list item 3 so that it doesn't disrupt the list itself.

Example:

3. List item.

   <p>Some code

This will probably be enough to let you suggest an edit; I have forgotten the exact rules.