Document Lazy Array manipulation in front

[jf-viguier]

It's a common case to try to add custom data to the lazy arrays in front for smarty (cart, product listing, product, ...) How to use hooks actionPresent[entities], $presentedObject->offsetSet() appendArray can also been used : $productLazyArray->appendArray([ 'extra_reference' => '123', 'extra_description' => 'Bla' ]);