Update index.html

Except for creating a global Y variable, that code does exactly the same thing as this code:

YUI().use('node', 'event', function (Y) {
    // Do stuff with node and event.
});

If you wanted to, you could create a global Y variable using the shorter style as well:

var Y = YUI().use('node', 'event', function (Y) {
    // Do stuff with node and event.
});