Add examples of radio and checkbox legends that are not page headings

[fofr]

Every example shown has isPageHeading set to true: https://design-system.service.gov.uk/components/radios/ https://design-system.service.gov.uk/components/checkboxes/

It's not clear from the examples:

• that a legend doesn't need to have a heading element within it
• what the markup should be for a legend that is not a page heading

[joelanman]

Mentioned here, I think we only tackled part of it:

https://github.com/alphagov/govuk-design-system/issues/1021

[fofr]

This had a knock-on effect which meant a formbuilder gem a few services are using has defaulted to using H1s in places that aren't appropriate.

[kellylee-gds]

Discussed with the team at triage today.

What

Add examples of legends that are not page headings to our form components.

Why

Without these examples some users assume that the only way to add legends is as headings.

Who needs to know about this

Content designer, developers

Done when

Example and additional guidance added to:

• [x] Checkboxes
• [x] Character count
• [x] Date input
• [x] Radios
• [x] Text input
• [x] Text area

Then:

• [ ] 2i'd
• [ ] Published