README: Change structure a bit

These scripts will need to be moved to a scripts/ directory anyway, so
might as well have it be a submodule of another repository.

README.md

@@ -19,13 +19,17 @@ ptouch.pl uses the following modules:
 
 ## How to use
 
-You'll need to create the following directories:
+Make an initial directory with the following structure:
 
+* site_dir/
   * posts/
   * pages/ - Templated pages
   * assets/ - Static assets
   * templates/ - Templates you can call with `include_tmpl`
 
+Either clone this repository to site_dir/scripts/, or add this
+repository as a git submodule.
+
 To make a new post, create a file with the following format in the
 posts/ folder: