fix demo link

Author: Matt Parnell

README.md

@@ -6,7 +6,7 @@
 
 ## What's new in version 2.0
 
-The biggest change is that your nested list can now behave as a tree with expand/collapse funcionality. Simply set `isTree` to **true** in the options and you are good to go! Check the [demo](http://htmlpreview.github.io/?https://raw.githubusercontent.com/ilikenwf/nestedSortable/2.0alpha/example.html) out to see what can be done with nestedSortable and a little CSS. (Note that all **nestedSortable** does is to assign/remove classes on the fly)  
+The biggest change is that your nested list can now behave as a tree with expand/collapse funcionality. Simply set `isTree` to **true** in the options and you are good to go! Check the [demo](http://ilikenwf.github.io/example.html) out to see what can be done with nestedSortable and a little CSS. (Note that all **nestedSortable** does is to assign/remove classes on the fly)  
 Also:
 - **isAllowed** function finally works as expected, see the docs below
 - Fixed: a small bug in the **protectRoot** function
@@ -55,7 +55,7 @@ Please note: every `<li>` must have either one or two direct children, the first
 
 Also, the default list type is `<ol>`.
 
-*This is the bare minimum to have a working nestedSortable. Check the [demo](http://htmlpreview.github.io/?https://raw.githubusercontent.com/ilikenwf/nestedSortable/2.0alpha/example.html) out to see what can be accomplished with a little more.*
+*This is the bare minimum to have a working nestedSortable. Check the [demo](http://ilikenwf.github.io/example.html) out to see what can be accomplished with a little more.*
 
 ## Custom Options