add VPN networking

source/handbook/infrastructure/production-architecture/index.html.md

@@ -107,6 +107,18 @@ IP space: `10.128.0.0/12`
 | WebStaging        | WebStaging        | WebStaging        | 10.132.8.0/23 | Services            |
 | StorageStaging    | StorageStaging    | StorageStaging    | 10.133.2.0/23 | Storage             |
+### Remote Access
+
+Virtual Network Name: `GitLabRemoteAccess`
+
+Resource Group: `GitLabRemoteAccess`
+
+IP Space: `10.254.0.0/16`
+
+| Resource Group    | Availability Set  | Subnet Name       | Subnet Range  | Friendly group name       |
+|:------------------|:------------------|:------------------|:--------------|:--------------------------|
+| ExternalVPNEng    | ExternalVPNEng    | ExternalVPNEng    | 10.254.1.0/24 | External VPN Engineering  |
+
 ## Azure