feat(library/init/nat): add missing decidable_ge and decidable_lt
feat(library/init/nat): add missing decidable_ge and decidable_lt

levnach/lean,leanprover/lean,soonhokong/lean-windows,leodemoura/lean,soonhokong/lean,eigengrau/lean,johoelzl/lean,c-cube/lean,leanprover/lean,leodemoura/lean,johoelzl/lean,eigengrau/lean,johoelzl/lean,htzh/lean,Kha/lean,avigad/lean,digama0/lean,soonhokong/lean,rlewis1988/lean,c-cube/lean,fpvandoorn/lean,UlrikBuchholtz/lean,UlrikBuchholtz/lean,digama0/lean,htzh/lean,fpvandoorn/lean,javra/lean,javra/lean,Kha/lean,fgdorais/lean,soonhokong/lean-windows,fgdorais/lean,sp3ctum/lean,rlewis1988/lean,c-cube/lean,fpvandoorn/lean2,fpvandoorn/lean2,levnach/lean,soonhokong/lean-windows,htzh/lean,fpvandoorn/lean2,soonhokong/lean-osx,sp3ctum/lean,leodemoura/lean,soonhokong/lean-osx,digama0/lean,leanprover-community/lean,fpvandoorn/lean,dselsam/lean,digama0/lean,leanprover/lean,rlewis1988/lean,johoelzl/lean,fpvandoorn/lean,soonhokong/lean-windows,leanprover-community/lean,eigengrau/lean,soonhokong/lean,avigad/lean,leanprover/lean,leanprover-community/lean,UlrikBuchholtz/lean,Kha/lean,Kha/lean,dselsam/lean,fgdorais/lean,javra/lean,dselsam/lean,levnach/lean,johoelzl/lean,soonhokong/lean-osx,fgdorais/lean,soonhokong/lean-windows,leanprover-community/lean,avigad/lean,digama0/lean,soonhokong/lean,fpvandoorn/lean,rlewis1988/lean,rlewis1988/lean,sp3ctum/lean,htzh/lean,eigengrau/lean,rlewis1988/lean,UlrikBuchholtz/lean,avigad/lean,leanprover/lean,fgdorais/lean,dselsam/lean,UlrikBuchholtz/lean,soonhokong/lean,avigad/lean,leodemoura/lean,leanprover/lean,leodemoura/lean,fpvandoorn/lean,sp3ctum/lean,c-cube/lean,Kha/lean,leanprover-community/lean,soonhokong/lean-osx,johoelzl/lean,soonhokong/lean-osx,c-cube/lean,javra/lean,Kha/lean,fgdorais/lean,levnach/lean,dselsam/lean,sp3ctum/lean,leanprover-community/lean,dselsam/lean,javra/lean,leodemoura/lean,avigad/lean,htzh/lean,digama0/lean,fpvandoorn/lean2,eigengrau/lean,fpvandoorn/lean2,levnach/lean