Update downloads-main.md
Update downloads-main.md

Added "Haskell IDEs & other distributions" paragraph
gbaz/hl,haskell-infra/hl,haskell-lang/haskell-lang,haskell-infra/hl,gbaz/hl,gbaz/hl,haskell-lang/haskell-lang,haskell-lang/haskell-lang,haskell-infra/hl