more details in readme

readme.markdown

@@ -4,3 +4,15 @@ jQuery Accessible Longdesc Plugin
 making the Longdesc content available to users without assistive technologies
 
 [demo](http://blog.ginader.de/dev/jquery/longdesc/examples/webaim/index.php)
+
+The 3 images on the demo page each have a different longdesc attribute:
+
+1. longdesc pointing to a page fragment: description.php#the-description (only that fragment will be loaded)
+2. longdesc pointing to a page: description.php (the whole page will be loaded)
+3. no longdesc attribute
+
+known limitations:
+
+1. breaks ie6 at the moment
+2. the info icon we're using is not being displayed in any internet explorers (me might need to use an image after all)
+3. only descriptions on the same server can be loaded due to the ajax same origin policy