Add a quick howto to README

Hi,

I needed to include libchart in a module I've written and though it would be a good idea to put it in sites/all/libraries and use the libraries module. Its my fist time to use the libraries module so I read the README :-) .... and its wasn't clear how to get going.

Anyway what I did in the custom module was as follows:

$file=libraries_get_path('libchart/classes/libchart.php');
  //dsm($file);
  if (is_file($file)) {
    require_once $file;
  } else {
    drupal_set_message('Could not load $file');
  }

If this is the right thing for such use cases, maybe add it to the README?