Add "Hint"-button to self-service-portal birth date input field

[dkehne]

Is your feature request related to a problem? Please describe.
When entering the birth date in our self service portal there should be a hint: "Bei Minderjährigen unter 16 Jahren darf der KoblenzPass nur mit Einverständnis der Erziehungsberechtigten abgerufen werden."

Describe the solution you'd like
Maybe a hint-button or "question mark" symbol next to the input field?

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
is not time critical - can be implemented in first part of 2025