Documentation improvements

[andymantell]

Discussed in https://github.com/surevine/govuk-react-jsx/discussions/121

^{Originally posted by UPLukeet October 7, 2021} I think the install instructions could be much clearer for instance the fact you need to import the gov css file is never mentioned. I also think interaction with components need to take props like a standard react component <Input value={} onChange={} /> or the way you interact with them currently should be better written up. For instance storybook should list all the props for each element and what values they accept(string, boolean, etc).