chore(library/algebra/ordered_field): generalize theorem from reals
chore(library/algebra/ordered_field): generalize theorem from reals

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