Change path to use XDG directory sheme

Put i3 config file in .config folder.

Install/i3-custom

@@ -3,5 +3,5 @@
 # Install i3 config
 # You must have installed the i3 package before
 
-mkdir ~/.i3
-cp ./Templates/i3/config ~/.i3/
+mkdir --parents ~/.config/i3
+cp --update --link ./Templates/i3/config ~/.config/i3/