Added more information regarding supported file types. Related to MDL…

…-7418 fix

lang/en_utf8/help/lesson/mediafile.html

@@ -4,4 +4,18 @@
 Also, a link will be printed out on every lesson page that re-opens the pop-up if necessary.</p>
 
 <p>Optionally a "Close Window" button be printed at the bottom of the pop-up and the 
-height and width of the window can be set as well.</p>
+height and width of the window can be set as well.</p>
+
+<p>Supported embedded file types:
+    <ul>
+        <li>MP3</li>
+        <li>Media Player</li>
+        <li>Quicktime</li>
+        <li>Realmedia</li>
+        <li>HTML</li>
+        <li>Plain Text</li>
+        <li>GIF</li>
+        <li>JPEG</li>
+        <li>PNG</li>
+    </ul>
+    All other file types will default to a link for download.</p>