feat(topology/constructions): a finite product of discrete spaces is discrete (#6088)
feat(topology/constructions): a finite product of discrete spaces is discrete (#6088)

From `lean-liquid`.

Co-authored-by: Scott Morrison <63f04b4d96235eb042cc46d94f14d241d2a26722@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib