Make expected format of input in user settings clearer

What does this MR do?

This MR makes it easier to add personal data in the user settings or to change it. It hopefully also nudges more people towards using full phone numbers including the country code. Note that the phone number example is also used during the registration process so this adds some consistency in that regard.

How confident are you it won't break things if deployed?

97.2%

Links to related issues

How to test

Screenshots (if applicable)

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• used "state:" labels to track this MR's state until it was beta tested
• added an entry to CHANGELOG.md
• added a short text that can be used in the release notes
• Once your MR has been merged, you are responsible to create a testing issue in the Beta Testing forum: https://foodsharing.de/?page=bezirk&bid=734&sub=forum
  • Consider writing a detailed description in German.
  • Describe in a few sentences, what should be tested from a user perspective.
  • Also mention different settings (e.g. different browsers, roles, ...) how this change can be tested.
  • Be aware, that also non technical people should understand.

Release notes text in German

Erkläre das erwartete Format von Telefonnummern und Geburtsdatum in den persönlichen Einstellungen.