Homepage improvement: ML at the top and move the Slang launch deck below the fold.

[bmillsNV]

Need to highlight Slang ML at the top of the homepage.

We can remove the "View Slang Launch Deck" button - as this is already included in the press releases / News.

In place of the "View Slang Launch Deck" we can highlight Slang is for Machine Learning - basically the SlangPy section below - but rename it and make it more Machine Learning focused.

[aidanfnv]

Closed by merging #92