It creates ID for your headers, and attach a hover anchor to them. ABSOLUTE development laziness, I love that.
Bonus: just adding the AnchorJS library + the JS snippet to your site will just work as fine!
The Bootstrap Callout styles in their documentation is really a nice way to draw attention to important information. For some reason these Callouts are not included in the actual Bootstrap distribution.
Here is my interpretation of the missing CSS code for generic Bootstrap Callouts. The color codes for the info, warning, and danger Callouts are a direct pull from their live CSS for the docs, so I added styles for default, success, and primary.