[arch-general] /etc/shells should keep /bin/zsh

I know arch-general si not for reporting bugs and I'm not trying to rush anyone, but it's been already a month of confusion wrt https://projects.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/zsh&id=c84d9770988fdc0f2e6c7bd5fa748d5a18580fb4 https://bugs.archlinux.org/task/35724