chore(library/data/nat/div): move instances to top-level
chore(library/data/nat/div): move instances to top-level

avigad/lean,leanprover-community/lean,dselsam/lean,johoelzl/lean,soonhokong/lean-windows,fgdorais/lean,fgdorais/lean,leanprover-community/lean,johoelzl/lean,leanprover/lean,Kha/lean,avigad/lean,Kha/lean,Kha/lean,soonhokong/lean-osx,soonhokong/lean-osx,soonhokong/lean-osx,dselsam/lean,dselsam/lean,digama0/lean,soonhokong/lean-windows,soonhokong/lean-windows,leodemoura/lean,johoelzl/lean,leanprover/lean,leanprover/lean,rlewis1988/lean,fpvandoorn/lean,digama0/lean,leanprover/lean,Kha/lean,avigad/lean,leodemoura/lean,fpvandoorn/lean,rlewis1988/lean,Kha/lean,leodemoura/lean,fgdorais/lean,avigad/lean,leanprover-community/lean,fpvandoorn/lean,soonhokong/lean-windows,leodemoura/lean,dselsam/lean,digama0/lean,rlewis1988/lean,leanprover/lean,johoelzl/lean,rlewis1988/lean,fgdorais/lean,soonhokong/lean-windows,avigad/lean,dselsam/lean,rlewis1988/lean,fgdorais/lean,soonhokong/lean-osx,dselsam/lean,fgdorais/lean,digama0/lean,digama0/lean,fpvandoorn/lean,fpvandoorn/lean,johoelzl/lean,avigad/lean,leanprover-community/lean,fpvandoorn/lean,leanprover/lean,leodemoura/lean,rlewis1988/lean,soonhokong/lean-osx,johoelzl/lean,leodemoura/lean,leanprover-community/lean,leanprover-community/lean,Kha/lean,digama0/lean