Since the community package doesn't include the fish completions found
upstream, we install them here instead. There is already a bug report
about the fish completions, and when it eventually gets fixed, these
steps can be removed from the PKGBUILD.
Bug report: https://bugs.archlinux.org/task/55786
Made dependency lists a bit more consistent and reverted some of the
Arch Linux wording since it felt a bit off. Even the official website
refers to Arch Linux as Arch from time to time.