Updated default config.yml to include a commented postgres sink example with pruning enabled

cmd/weatherfeeder/config.yml

@@ -92,6 +92,15 @@ sinks:
       url: nats://nats:4222
       exchange: weatherfeeder
 
+#  - name: pg_weatherfeeder
+#    driver: postgres
+#    params:
+#      uri: postgres://weatherdb:5432/weatherdb?sslmode=disable
+#      username: weatherdb
+#      password: weatherdb
+#      prune: 3d
+#      # Prunes rows older than now-3d on each write transaction.
+
 #  - name: logfile
 #    driver: file
 #    params:
@@ -104,5 +113,8 @@ routes:
   - sink: nats_weatherfeeder
     kinds: ["observation", "forecast", "alert"]
 
+#  - sink: pg_weatherfeeder
+#    kinds: ["observation", "forecast", "alert"]
+
 #  - sink: logfile
 #    kinds: ["observation", "alert", "forecast"]