Some update for the voting tool

Part of #975

What does this MR do?

• adds Markdown support for the description text of polls
• adds the link to the poll list to the groups menu as well (it's only in the region's menu yet)
• moves the "you can't vote" hints up on the poll page, so that people see it before filling out the form

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

Very much

Screenshots

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as ambassador
3. Create a new poll with markdown in the description
4. The markdown should be visible on the poll's page

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
• use "state:" labels to track this MR's state until it was beta tested
• added an entry to CHANGELOG.md
• add 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 Beta Testing Repo:
  • 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

(A short text that will appear in the release notes and describes the change for non-technical people. Not always necessary, e.g. not for refactoring.)