Add link to wiki page on calendar page

Closes #1099 (closed)

What does this MR do?

Adds a link to https://wiki.foodsharing.de/Kalenderexport which will contain hints about using the calendar export function.

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

Very sure

How to test

1. Checkout branch locally
2. Login as foodsaver
3. Go to settings -> calendar and see the link

Screenshots (if applicable)

3

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