Improve the docs

[sanketsahu]

I feel the intro discussion of the React to EU talk is slightly misguiding.

1. Passing aria-required as true would only make it required for a11y users but would not change the behavior of the input to actually be required. it is better to use the html required attribute

2. In the checkbox example, since you are using the html checkbox, there is no need to use the aria-checked attribute, and since the checkbox is already nested inside the label there is no need to use the aria-labelledby. the usage of aria-labelledby is also incorrect as it only works with IDs but you are referring to a classname.

You slightly touch on the native a11y capabilities of the input type checkbox while building the common component later.