Expand documentation of fieldset to discuss when to add role="group"

[edwardhorsford]

The date component has role="group" on its fieldset. The fieldset component example doesn't.

Via @36degrees, this is what the code has to say:

We override the fieldset's role to 'group' because otherwise JAWS does not
announce the description for a fieldset comprised of text inputs, but
adding the role to the fieldset always makes the output overly verbose for
radio buttons or checkboxes.

If this is still true, then it would be good to add something to the fieldset example discussing it. It may not be relevant to radios and checkboxes, but I suspect most usages of the fieldset component itself are likely for other elements.

Suggestion

• Add another example to fieldset, possibly covering hints and errors, but also with role="group"
• Add a paragraph of text discussing when to use it.