Integrate elm-docs-preview application documentation

[ChrisWellsWood]

A new version of elm-docs-preview has recently been released and it adds a cool feature called application documentation, which, as the name suggests, let you build documentation for your application. I've been messing about with this and think that it is really useful. Aside from the obvious benefits of encouraging you to actually document your application, it also enables you to browse the documentation for your dependencies offline. Here's an example that the author made from Richard Feldman's Real World SPA: https://elm-doc-preview.netlify.com/?repo=rlefevre/elm-spa-example

I think this might be the right kind of sensible default to add to create-elm-app, interested to hear what others think.

See this thread on Elm Discourse for more information.

[halfzebra]

Hi Chris!

I like the idea of introducing this. :+1: Would you like to work on a PR?

[ChrisWellsWood]

Yes, I will do. I should have some time over the next week.

[halfzebra]

Nice, please let me know if you'll need any help!