Update parking infos and link everywhere

docs/caravans.md

@@ -4,7 +4,7 @@ As with previous iterations of CCCamp, you will be able to purchase a *caravan t
 
 If you're planning to attend CCCamp with a caravan, please keep the following in mind:
 
-* Parking your vehicle in the caravan area *requires a caravan ticket* (not the parking area – a regular parking ticket is fine for that)
+* Parking your vehicle in the caravan area *requires a caravan ticket* (not in the parking area – a regular [parking ticket](https://events.ccc.de/camp/2023/infos/tickets.html#add-ons) is fine for that)
 * Please bring a 2 kg fire extinguisher if you have fire hazards in your vehicle, such as flammable gas bottles
 
 ## Infrastructure