Adding a comment describing the format

src/zoomifytilesource.js

@@ -3,6 +3,38 @@
     /**
      * @class ZoomifyTileSource
      * @classdesc A tilesource implementation for the zoomify format.
+     *
+     * A description of the format can be found here:
+     * https://ecommons.cornell.edu/bitstream/handle/1813/5410/Introducing_Zoomify_Image.pdf
+     *
+     * There are two ways of creating a zoomify tilesource for openseadragon
+     *
+     * 1) Supplying all necessary information in the tilesource object. A minimal example object for this method looks like this:
+     *
+     * {
+     *      type: "zoomifytileservice",
+     *      width: 1000,
+     *      height: 1000,
+     *      tilesUrl: "/test/data/zoomify/"
+     * }
+     *
+     * The tilesize if currently hardcoded to 256. The tileUrl must the the path to the image _directory_.
+     *
+     * 2) Loading image metadata from xml file: (CURRENTLY NOT SUPPORTED)
+     *
+     * When creating zoomify formatted images one "xml" like file with name ImageProperties.xml
+     * will be created as well. Here is an example of such a file:
+     *
+     * <IMAGE_PROPERTIES WIDTH="1000" HEIGHT="1000" NUMTILES="21" NUMIMAGES="1" VERSION="1.8" TILESIZE="256" />
+     *
+     * To use this xml file as metadata source you must supply the path to the ImageProperties.xml file and leave out all other parameters:
+     * As stated above, this method of loading a zoomify tilesource is currently not supported
+     *
+     * {
+     *      type: "zoomifytileservice",
+     *      tilesUrl: "/test/data/zoomify/ImageProperties.xml"
+     * }
+
     *
     * @memberof OpenSeadragon
      * @extends OpenSeadragon.TileSource