Service-catalog: Add hover anchor links to all of our headings, not just H1

[carolynvs]

On svc-cat.io we have hover anchor links to help people copy deep links to sections within our docs. However not all of the headings work with it at the moment.

For example, all of the headings on the dev guide page

https://svc-cat.io/docs/devguide

It works on the install page though, (hover over Step 1 - Prerequisites) to see it

https://svc-cat.io/docs/install/

The documentation site's sass and js are all in https://github.com/kubernetes-incubator/service-catalog/tree/master/docsite.

[MHBauer]

/joke What's wrong with our documentation having sass? I think most docs aren't sassy enough and can use some more sass. /joke

[carolynvs]

Implemented in #2340