Document how write a Dancer2 CGI app

I worked with @xsawyerx today and we figured out how to write a Dancer2 app in CGI. We feel like it should be documented but we're not sure where:

use Dancer2;
use Plack::Loader;
use Template::Provider::FromDATA;

# Tell Dancer to use the DATA section for templates                                                                                                                                                                                                                                                                                                                                                     
my $provider = Template::Provider::FromDATA->new( { CLASSES => __PACKAGE__ } );
set engines => {template => { template_toolkit => { LOAD_TEMPLATES => [ $provider ] }}};
set template => 'template_toolkit';

get '/' => sub {
    template 'mytemplate' => { bar => "foo" };
};
Plack::Loader->auto->run(main->to_app);

__DATA__                                                                                                                                                                                                                                                                                                                                                                                                
                                                                                                                                                                                                                                                                                                                                                                                                        
__mytemplate.tt__                                                                                                                                                                                                                                                                                                                                                                                       
Flib [% bar %]                                                                                                                                                                                                                                                                                                                                                                                          
                                                                                                                                                                                                                                                                                                                                                                                                        
__anothertemplate.tt__                                                                                                                                                                                                                                                                                                                                                                                  
Something else here.

Start with the CGI application example in the issue and inspect the repository's existing documentation structure to find the appropriate location. Document the demonstrated Dancer2 CGI setup, including the embedded templates, so a reader can follow it as a complete example.