Fix typo with incorrect class in docs for required checkbox and variants

[paustint]

The docs indicate to use an incorrect classname wich does not reflect what is shown in the examples

Please refer to our Commit Guidelines for documenting changes.

Changes proposed in this pull request:

• Fixed radio button docs to show correct class name for required components

The code examples were correct, but the surrounding text in the docs was not correct.

Acceptance Criteria

General

• [x] (n/a) Tested on desktop (see supported browsers)
• [x] (n/a) Tested on mobile (for responsive or mobile-specific features)
• [x] (n/a) Confirm Accessibility
• [x] (n/a) Confirm RTL

Fix

• [x] (n/a) Reference Bug work item number in description
• [x] (n/a) Add tests to ensure bug does not happen again
• [x] (n/a) Add component specific Release notes mentioning the changes