Add mockup of demonstration of new feature

[jssmith1]

Maybe link coloring for visited sites

[jssmith1]

@CaptainEmerson: you suggested mocking up the animation feature. Wasn't sure how that would come across staticlly. Instead mocked the the (admittedly less exciting) link color changing feature.

Thoughts?

[jssmith1]

• [x] add browser tab above and some code bellow