Added documentation for the new flexibility

lib/Plack/Handler/Apache2.pm

@@ -135,14 +135,41 @@ Plack::Handler::Apache2 - Apache 2.0 handlers to run PSGI application
   Plack::Handler::Apache2->preload("/path/to/app.psgi");
   </Perl>
 
+  # Or create your own handler:
+  package My::ModPerl::Handler;
+  use Plack::Handler::Apache2;
+
+  sub get_app {
+    # magic!
+  }
+
+  sub handler {
+    my $r = shift;
+    my $app = get_app();
+    Plack::Handler::Apache2->call_app($r, $app);
+  }
+
 =head1 DESCRIPTION
 
 This is a handler module to run any PSGI application with mod_perl on Apache 2.x.
 
+=head1 METHODS
+
+=head2 call_app($r, $app)
+
+The mod_perl handler in this package loads the app and calls this method.  If
+you'd like to do something different, you can still make use of this module by
+preparing $r and $app in some other fashion and calling this as a class
+method.
+
 =head1 AUTHOR
 
 Tatsuhiko Miyagawa
 
+=head1 CONTRIBUTORS
+
+Paul Driver
+
 =head1 SEE ALSO
 
 L<Plack>