Landing page

[tpluscode]

Re. #14 (review)

@alien-mcl and I discussed that we'll need a home page for the extensions, which will link to the specific documents.

That could one of two. Either a small bikeshed "spec" (how SPARQL and OWL does that) or a page using the http://www.hydra-cg.com template (how DASH does it).

I have no strong opinion and might as well do a coin toss. Opinions welcome

[alien-mcl]

I do not have any specific thoughts neither. For not I feel a spec-like landing page fits better.