For each HTTP request, Phusion Passenger will automatically look for a corresponding
page cache file, and serve that if it exists. It does this by appending ".html" to
the filename that the URI normally maps to, and checking whether that file exists.
This check occurs after checking whether the original mapped filename exists (as part
of static asset serving). All this is done without the need for special mod_rewrite
rules.

For example, suppose that the browser requests '/foo/bar'.

1. Phusion Passenger will first check whether this URI maps to a static file, i.e.
   whether the file 'foo/bar' exists in the web application's 'public' directory.
   If it does then Phusion Passenger will serve this file through the web server immediately.
2. If that doesn't exist, then Phusion Passenger will check whether the file
   'foo/bar.html' exists. If it does then Phusion Passenger will serve this file
   through the web server immediately.
3. If 'foo/bar.html' doesn't exist either, then Phusion Passenger will forward the
   request to the underlying web application.

Note that Phusion Passenger's page caching support doesn't work if your web
application uses a non-standard page cache directory, i.e. if it doesn't cache to
the 'public' directory. In that case you'll need to use mod_rewrite to serve such
page cache files.