refactor(download/index): change wording
refactor(download/index): change wording

leanprover/leanprover.github.io,soonhokong/leanprover.github.io,avigad/leanprover.github.io,avigad/leanprover.github.io,soonhokong/leanprover.github.io,fpvandoorn/leanprover.github.io,leanprover/leanprover.github.io,avigad/leanprover.github.io,fpvandoorn/leanprover.github.io,soonhokong/leanprover.github.io,fpvandoorn/leanprover.github.io,leanprover/leanprover.github.io