Make haskell-platform page redirect to the downloads page

[MorrowM]

Now that the Downloads page is in decent shape I think it might be time to remove the page for the Haskell Platform and make it redirect to the downloads page. As of the time of posting haskell-platform supersedes the downloads page in the search results for "install haskell" on both Google and DuckDuckGo. I've seen a number of people struggling with their GHC/cabal installations because of this, and they end up switching to GHCup anyways, which wastes their time.

A less extreme measure would be to put a deprecation banner up, but that wouldn't be a very smooth experience for newcomers in my opinion.

[tomjaguarpaw]

Thanks very much for reporting this. I agree. There is some related discussion in #136 (comment)

[tomjaguarpaw]

Fixing that will close this issue too: haskell-infra/haskell-admins#4

[tomjaguarpaw]

Fixed by #149 (comment)