Issue title: Example 2.12 Comparison operators, line 8, shows extraneous markup
 Issue body: I think that line 8 in example 2.12:

```
foo == baz;   <span class="bold"><strong>// returns true; careful!</strong></span>
```

should read:

```
foo == baz;   // returns true; careful!
```

(Maybe the word "careful!" is meant to be highlighted?)

 Comments: 
 Comment 0: I think this is only an issue when this content was in jqfundamentals with syntaxhighlighter. Once/if this chapter is switched to markdown, we will be all good.

 Comment 1: Issue is still present, should probably be changed for professionalism :)

 Comment 2: Fixed: https://github.com/jquery/web-learn-jquery-com/commit/888eec012e631187f090937f88ea73f50dc096d9

Please remember that as per @gjohnson's last message, we're going to be moving to only having markdown based files in these folders with compiled versions being available in the built version of the site at some point. Right now theres a combination of precompiled older chapters and separated onces that have been since updated hanging. We should aim to do a clean-up at some point.

{'source': 'GithubIssues', 'repo_name_with_owner': 'jquery/learn.jquery.com', 'issue_id': 1149829, 'repo_stars': 913.0}