Export SectionSelect or remove from docs

[gpoitch]

I see the new SectionSelect listed in the README as a usable component, however it is not exported. I also see the PR for it says that it's only meant to be a demo.

I think it should either be exported or removed from the README. Let me know and I can PR.

[joshfrench]

Yup, that should be exported. Good catch, thanks!

[joshfrench]

Thanks! Published.