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.
This change shouldn't be made. Even if it happens to silence HTML validation errors, it is incorrect according to WAI-ARIA and won't be helpful to screen reader users. Here is what WAI-ARIA says about <code>role="option"</code>: 
"Authors MUST ensure elements with role option are contained in, or owned by, an element with the role listbox. Options not associated with a listbox might not be correctly mapped to an accessibility API."

So it is odd that the validator is not flagging an error for putting an "option" inside of a "menu" (clearly a bug in the validator if it considers it correct).