Fix #31: Enable anchor links for kroxylicious.io

[k-wall]

It looks like this:

[k-wall]

@gracegrimwood thank you.

One issue, can we make the anchoring relative to the black title area? In this case I would expect the "What is Kroxylicious" to be displayed immediately beneath the black title area.

Do you know the right way to fix this?

[gracegrimwood]

Took some digging because the usual solution (having the anchor link to an invisible div offset vertically up the page from the heading) isn't available to us because of the way we're injecting these anchors into the page. Turns out we can do it with the scroll-margin-top property instead, so I've submitted a PR to fix that here.