feat(library/logic/examples/propositional/soundness): cleanup precedence levels
feat(library/logic/examples/propositional/soundness): cleanup precedence levels

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