This commit adds two new scripts: `enable-multilib.sh` and `install-yay-arch.sh`. The `enable-multilib.sh` script enables multilib libraries by uncommenting the [multilib] section in `/etc/pacman.conf` and updating the system. The `install-yay-arch.sh` script installs yay, a package manager for Arch Linux, if it is not already installed. Both scripts include error handling and custom error messages.
