feat(pie-docs): DSW-2496 radio-group overview page

[jamieomaguire]

Describe your changes (can list changeset entries if preferable)

• Completed radio button overview page in docs site
• Added the missing index card for checkbox group
• Extended the error messaging for index cards to tell the developer where the missing image was expected to be

Author Checklist (complete before requesting a review)

• I have performed a self-review of my code
• I have reviewed the PIE Storybook/PIE Docs PR preview
• I have reviewed visual test updates properly before approving

Reviewer checklists (complete before approving)

Reviewer 1 - @siggerzz

• I have reviewed the PIE Storybook/PIE Docs PR preview
• If there are visual test updates, I have reviewed them

Reviewer 2 @raoufswe

• I have reviewed the PIE Storybook/PIE Docs PR preview
• If there are visual test updates, I have reviewed them

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1b846a4

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[raoufswe]

seems like one of the images isn't loading