Add a Machine Learning Julia landing page

[logankilpatrick]

It would be really nice to have a machine-learning Julia landing page. I will try to take a stab at this sometime soon.

[ablaom]

FYI: I generally point to https://alan-turing-institute.github.io/MLJ.jl/dev/ (rather than the MLJ repo). I suppose you're suggesting a replacement for that?

[math4mad]

Maybe I think like this https://sciml.ai

just like a collection of websites of Julia Machine Learning, main focus on Documents and Tutorials

[ablaom]

This is now work in progress. Standby for a new landing page soon.