add api doc links for uba and dwd

cron/scripts/ext_api_sync/dwd_api_sync.py

 #! /usr/bin/env python3
 
+# DWD Brightsky API docs: https://brightsky.dev/docs/#/operations/getWeather
+
 import requests
 import os
 import logging

cron/scripts/ext_api_sync/uba_api_sync.py

 #! /usr/bin/env python3
 
+# UBA API docs: https://www.umweltbundesamt.de/daten/luft/luftdaten/doc
+
 import requests
 import os
 import logging