XmlStore docs say "item must be an XML element"

[Sam Foster]

Docs for all the api methods in dojox/data/XmlStore.js say "item: An XML element" and, description: 'item' must be an XML element.

but the first line of each method is var element = item.element;

The items in this implementation are actually instances of vuitx.data.XmlItem?, which have an element property whose value is the element.

[Jared Jurkiewicz]

(In [11714]) Docs update. fixes #5245

[Jared Jurkiewicz]

(In [11715]) Docs update. refs #5245