[wolfsmartset] Fix link to external documentation (openhab#13996)

Update link to current document from Wolf download center.
Fixes openhab#13995.

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

bundles/org.openhab.binding.wolfsmartset/README.md

@@ -117,7 +117,7 @@ All devices able to be connected to www.wolf-smartset.de
 
 ### Related Documentation from WOLF
 
-https://www.wolf.eu/fileadmin/Wolf_Daten/Dokumente/FAQ/3065655_201711.pdf
+https://oxomi.com/service/json/catalog/pdf?portal=2024876&catalog=10406695
 
 | Heating system                            | WOLF Link home        | WOLF Link pro      |
 |-------------------------------------------|-----------------------|--------------------|