Update parking trailhead

via StreetComplete_ee 57.0

Attached photo(s):
https://westnordost.de/p/210101.jpg
https://westnordost.de/p/210102.jpg
https://westnordost.de/p/210103.jpg
https://westnordost.de/p/210104.jpg
https://westnordost.de/p/210105.jpg