announce geoip_url in provider.json

api_specs/v4/provider.json

@@ -6,6 +6,7 @@
   "info_url": "https://riseup.net/vpn",
   "tos_url": "https://riseup.net/tos",
   "help_url": "https://riseup.net/support",
+  "geoip_url": "https://api.black.riseup.net:9001/json",
   "donations": true,
   "default_language": "en",
   "description": {