[enh] add vpn to format and spec

ispformat/schema/0.1/isp.json

@@ -107,7 +107,7 @@
                 },
                 "technologies": {
                     "type": "array",
-                    "items": { "enum": [ "ftth", "fttb", "dsl", "wifi" ] }
+                    "items": { "enum": [ "ftth", "fttb", "dsl", "wifi", "vpn" ] }
                 },
                 "area": {
                     "$ref": "http://json-schema.org/geojson/geojson.json#"

ispformat/specs/0.1/isp-schema-spec.rst

@@ -78,6 +78,8 @@ dsl
   Internet access provided over a phone line. This encompass ADSL, VDSL, SDSL and all the other xDSL technologies.
 wifi
   Internet access provided over Wi-Fi.
+vpn
+  Virtual Private Network access.
 
 This list is not exhaustive. Please contact us to add more.