Add autocomplete standard to docs.

See:
http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#autofilling-form-controls:-the-autocomplete-attribute
Add autocomplete standard to docs.

See: http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#autofilling-form-controls:-the-autocomplete-attribute