move the install script outside of the dotfiles

[amtoine]

The install.sh install script to install the GOAT files on a post-installed ArchLinux-based system really is not a dotfile and deserves its own repo.

• the repo: https://github.com/goatfiles/install

motivation

• keep only dotfiles in this repo
• shed light onto the install script
• allow the design of more installation scripts, e.g. to install the GOAT files on different distros, in a separate place

depends on

we'll wait for the merge of the following PRs before moving the install.sh script to its new repository :+1:

• 68

• 67