AUR updates

Updated link to AUR pkg. Arch users, see:

- https://aur.archlinux.org/packages/zeromq-git/
- https://aur.archlinux.org/packages/czmq-git/
- https://aur.archlinux.org/packages/czmqpp-git/
- https://aur.archlinux.org/packages/secp256k1-git/
- https://aur.archlinux.org/packages/libbitcoin-git/
- https://aur.archlinux.org/packages/libbitcoin-protocol-git/
- https://aur.archlinux.org/packages/libbitcoin-client-git/
- https://aur.archlinux.org/packages/libbitcoin-explorer-git/