Added the dotfiles for the Fish shell

.chezmoiroot

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+/home

home/private_dot_config/fish/conf.d/greeting.fish

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+# Don't greet the user every time they open the shell
+set fish_greeting

home/run_onchange_before_archlinux.sh.tmpl

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+#!/bin/bash
+
+{{ if false -}}
+echo "This script must be run in Arch Linux"
+exit 1
+{{ end -}}
+
+set -eu
+
+{{ if ne .chezmoi.osRelease.id "arch" -}}
+echo "You're not running Arch Linux. Skipping..."
+exit 0
+{{ end -}}
+
+while true; do
+    read -p "Do you want to run the Arch Linux configuration script? [Y/n] " REPLY
+
+    # Treat an empty response as the default "Y"
+    REPLY=${REPLY:-Y}
+
+    case "$REPLY" in
+        y|Y) break ;;
+        n|N) exit 0 ;;
+        *) echo "Unrecognized option. Please answer Y or n." ;;
+    esac
+done
+
+set -x
+
+# Install the Fish shell
+sudo pacman --noconfirm -S fish
+sudo chsh -s "$(which fish)" $USER