some very basic documentation of the API

index.html

@@ -293,6 +293,28 @@
 <script src="js/impress.js"></script>
 <script>impress();</script>
 
+<!--
+    
+    The `impress()` function also gives you access to API to control the presentation.
+    
+    Just store the result of the call:
+    
+        var api = impress();
+    
+    and you will get three functions you can call:
+    
+        `api.next()` - moves to next step of the presentation,
+        `api.prev()` - moves to previous step of the presentation
+        `api.goto( stepElement ) - moves the presentation to given step element (the DOM element of the step).
+    
+    You can also simply call `impress()` again to get the API, so `impress().next()` is also allowed.
+    Don't worry, it wont initialize the presentation again.
+    
+    For some example uses of this API check the last part of the source of impress.js where the API
+    is used in event handlers.
+    
+-->
+
 </body>
 </html>