Add link to the full config template

For alacritty on GitHub.

Install/Templates/alacritty/alacritty.yml

@@ -1,3 +1,5 @@
+# Find template at https://github.com/alacritty/alacritty/blob/master/alacritty.yml
+
 window:
   decorations: full
   startup_mode: Windowed