Update HTML element table into four columns

[scottaohara]

After merging in the bigger updates of #265, #262 and #263, I want to create a fourth column in the element table to split apart the allowed roles for an element and the allowed attributes.

The third column would define the the ARIA roles which MAY be used.

The fourth column would define the aria-* attribute allowances AND restrictions.

Right now it's awkward that the 3rd column is titled "ARIA roles, states and properties which MAY be used", but notes about recommended usage of aria-* attributes, or restrictions are also provided in this column.