Update travel instructions

The B96 is closed behind Oranienburg due to construction work between Nassenheide und Teschendorf.

https://oranienburg.de/index.php?object=tx,2967.5&ModID=7&FID=2967.4046.1

docs/travel.md

@@ -202,7 +202,8 @@ But for some, travel by car is the only viable option, in that case:
 
  * Drive in direction Berlin until you reach the highway A10 "Berliner Ring" - the highway ring around the city.
  * Stay on the A10 until you reach the exit "Kreuz Oranienburg". Take the B96 direction Stralsund / Oranienburg.
- * Follow the B96 until you reach Gransee
+ * Follow the B96 until Oranienburg-Nord, then follow the U96 via Sommerfeld, Herzberg (Mark), Löwenberg back onto B96
+ * Follow the B96 again until you reach Gransee.
  * In Gransee turn right onto Templiner Str. L22 (Zehdenick)
  * Follow the L22 until you reach the junction with Granseer Str. and turn left onto Granseer Str. (Mildenberg)
  * Follow the signs pointing to "Ziegeleipark Mildenberg".