rc systemd: Make sure files are in the systemd directory

Fixes #2272

rc/extra/systemd.kak

@@ -6,4 +6,9 @@
 
 hook global BufCreate .*/systemd/.+\.(automount|conf|link|mount|network|path|service|slice|socket|target|timer) %{
     set-option buffer filetype ini
+
+    # NOTE: INI files define the commenting character to be `;`, which won't work in `systemd` files
+    hook -once buffer BufSetOption comment_line=.+ %{
+        set-option buffer comment_line "#"
+    }
 }