Describe the bug

The existing visible instructions for time picker aren't sufficient to prevent errors; we need to add clarity to the format and options to prevent users from typing in potentially invalid times.
See https://www.w3.org/TR/WCAG20/#minimize-error-cues for clarification on 3.3.2

Steps to reproduce the bug

1. Go to https://designsystem.digital.gov/components/time-picker/
2. View hh:mm
3. Try typing in 12:15
4. Try typing in 19:30

Findings: hh:mm may not provide enough instructions for a user to select a valid time.

Expected Behavior

Suggest adding more clear instructions. For example:

Start typing or select an AM or PM time in half-hour increments.

Screenshots

No response

System setup

No response

Additional context

FYI there's a related issue here for adding a 24 hour option #4947

Code of Conduct

• I agree to follow this project's Code of Conduct.
• I checked the current issues for duplicate bug reports.