fixed HTML validation errors found after JS insertion

Moved the `aria` attributes from the `a` to the `li` and changed the `role` to `option` as per @masterbee request.

Also fixed the `module` code because it was calling a `header` inside a `header`.

Still not validating at 100% because of the mobile menu but according to @masterbee we would need to rewrite this function to get this to validate.

Hope this is ok for my first JS change in WET.
I checked and this change should not be made. This is supposed to be a header element and not a div. This is consistent with what is done for all other overlays in WET.