Group pages should not be searchable

[imaustink]

Search results often include group pages like can-stache-bindings.syntaxes.html.

[chasenlehara]

@imaustink and I talked about punting this issue. I can see it both ways: pages that you can’t navigate to shouldn’t be generated (so they’re not part of the search index), but also group pages might be helpful for people searching.