adding link to dom tutorial for issue #346

Author: lauren mccarthy

lib/addons/p5.dom.js

@@ -3,10 +3,14 @@
  * <p>The web is much more than just canvas and p5.dom makes it easy to interact 
  * with other HTML5 objects, including text, hyperlink, image, input, video, 
  * audio, and webcam.</p>
- * <p>There are a set of creation methods, and some other stuff... @TODO.</p>
+ * <p>There is a set of creation methods, DOM manipulation methods, and
+ * an extended p5.Element that supports a range of HTML elements. See the 
+ * <a href="https://github.com/lmccart/p5.js/wiki/Beyond-the-canvas">
+ * beyond the canvas tutorial</a> for a full overview of how this addon works.
  *
  * <p>Methods and properties shown in black are part of the p5.js core, items in
- * blue are part of the p5.dom library. See the
+ * blue are part of the p5.dom library. You will need to include an extra file
+ * in order to access the blue functions. See the
  * <a href="http://p5js.org/libraries/#using-a-library">using a library</a>
  * section for information on how to include this library. p5.dom comes with
  * <a href="http://p5js.org/download">p5 complete</a> or you can download the single file