Clarify Readme.

[aviks]

No description provided.

[fredrikekre]

This repo should probably move to JuliaComputing org and be named something more apt, perhaps JuliaHubDocHostingRegistry.

[odow]

This repo should probably move to JuliaComputing org

I think this is quite important from a transparency point of view.

[mortenpi]

I am not taking a position here where the package should live, but technically, this is not used by JuliaHub directly, but by the DocumentationGenerator OSS package, which in turn is used by JuliaHub. So those two packages should stay together.

[odow]

It's fine for both packages to be open-source, but it's not really "here's a package that you can use to build all the docs, and by the way, we're using it for JuliaHub." It's more "here's a package to build JuliaHub, and you could use it too, if you like."