chore(doc/make/msys2): update msys2 build instructions
chore(doc/make/msys2): update msys2 build instructions

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