Readme with better instructions for how to make HTML work

and hinting at how to make EPUB books.

readme.org

@@ -55,6 +55,35 @@ todo (or substitute whatever other tag(s) you are interested in).
 | list     | txt     | Only generate list of sections.      |
 | static   | html    | Remove script link from HTML output. |
 
+** Styles and Scripts
+Generated *html* files use the included *gamebookformat.css* for
+styling and *gamebookformat.js* for scripting (except with the
+*htmlbook* or *static* options).
+You need those files in the same directory (folder) as
+your generated *html* file for it to look right. Of course
+for a more professional look you probably want to tweak that
+CSS and possibly the script to look better. A problem with
+using your own modified versions is that you have to manually
+merge them with future versions of the files provided with
+gamebookformat. To avoid that it is better to add
+styles and scripts using custom templates. There are
+some hooks in the standard templates to make it
+easy to add overrides without replacing anything (for
+instance by making a template with a *html/head-overrides.html* file).
+(TODO: Add example showing how to do that, because the last few
+sentences here probably did not make sense to anyone.)
+
+** EPUB
+There is no built-in support for generating EPUB books, however
+there are numerous tools out there to import one of the
+file formats generated by gamebookformat that can
+convert them to EPUB (and other ebook formats). The most
+suitable format is probably *html* with the *-o htmlbook*
+or *-o htmlbook* options. [[http://calibre-ebook.com/][Calibre]] seems to do a good job converting these
+to EPUB, so that should be a start. You probably want to
+do some experimentation to find a way that creates results
+you like.
+
 ** Number Map Files
 Whenever formatgamebook.py runs it looks for a file with the same
 name as the output file, but with a .map suffix (eg output.map if