Fix typo in index.html

wont -> won't

index.html

@@ -415,7 +415,7 @@ if ("ontouchstart" in document.documentElement) {
                 but it's optional - if not provided default transition duration for the presentation will be used.
     
     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.
+    Don't worry, it won't 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.