Library: Document that, when using requirejs, a page should only be instantiated after the whole library is loaded, otherwise it may fail to instantiate some widgets

We need to provide an example of a scenario where somebody uses the library using requirejs, and maybe skips init altogether. For example,

require([
    "jqm/widgets/popup",
    "jqm/widgets/listview",
    "jqm/widgets/page" ], function() {

    $( function() {
        $( "#start-page" ).page();
    });
};

Will not work if requirejs loads page after it has loaded popup and listview. We need to document that, in 1.4.x, one needs to require page before requiring any of the widgets:

require([
    "jqm/widgets/page" ], function() {

    require([
        "jqm/widgets/popup",
        "jqm/widgets/listview" ] ,function() {

        $( function() {
            $( "#start-page" ).page();
        });
    });
});