template.php

/**
 * Override or insert variables into the node template.
 */
function MYTHEME_preprocess_node(&$variables) {
  if ($variables['node']->type == 'article') {
    kpr($variables['node']);
    $node = $variables['node'];
    if (isset($variables['node']->field_file)) {
      $file = field_get_items('node', $node, 'field_file');
      $file = reset($file);
      kpr($file);
      $file = file_load($file['fid']);
      $file_uri = drupal_realpath($file->uri);
      kpr($file_uri);
      $variables['download_link'] = l('Download', $file_uri);
      kpr($variables['download_link']);
    }
  }
}

Remove the kpr's and change:

"article" to "developments"

"field_file" to "field_development_brochure"

print render the newly created $download_link variable