TF docs fix

modules/vpn/README.md

@@ -188,7 +188,7 @@ No modules.
 | <a name="input_network"></a> [network](#input\_network) | VPC network ID that should be used for deployment | `string` | n/a | yes |
 | <a name="input_project"></a> [project](#input\_project) | n/a | `string` | `null` | no |
 | <a name="input_region"></a> [region](#input\_region) | Region to deploy VPN gateway in | `string` | n/a | yes |
-| <a name="input_router_name"></a> [router\_name](#input\_router\_name) | Cloud router name. The router is created by the module | `string` | n/a | yes |
+| <a name="input_router_name"></a> [router\_name](#input\_router\_name) | Cloud router name. The router is created by the module | `string` | `null` | no |
 | <a name="input_vpn_config"></a> [vpn\_config](#input\_vpn\_config) | VPN configuration from GCP to on-prem or from GCP to GCP.<br>If you'd like secrets to be randomly generated set `shared_secret` to empty string ("").<br><br>Example:<pre>vpn_config = {<br>  router_asn    = 65000<br>  local_network = "vpc-vpn"<br><br>  router_advertise_config = {<br>    ip_ranges = {<br>      "10.10.0.0/16" : "GCP range 1"<br>    }<br>    mode   = "CUSTOM"<br>    groups = null<br>  }<br><br>  instances = {<br>    vpn-to-onprem = {<br>      name = "vpn-to-onprem",<br>      peer_external_gateway = {<br>        redundancy_type = "TWO_IPS_REDUNDANCY"<br>        interfaces = [{<br>          id         = 0<br>          ip_address = "1.1.1.1"<br>          }, {<br>          id         = 1<br>          ip_address = "2.2.2.2"<br>        }]<br>      },<br>      tunnels = {<br>        remote0 = {<br>          bgp_peer = {<br>            address = "169.254.1.2"<br>            asn     = 65001<br>          }<br>          bgp_peer_options                = null<br>          bgp_session_range               = "169.254.1.1/30"<br>          ike_version                     = 2<br>          vpn_gateway_interface           = 0<br>          peer_external_gateway_interface = 0<br>          shared_secret                   = "secret"<br>        }<br>        remote1 = {<br>          bgp_peer = {<br>            address = "169.254.1.6"<br>            asn     = 65001<br>          }<br>          bgp_peer_options                = null<br>          bgp_session_range               = "169.254.1.5/30"<br>          ike_version                     = 2<br>          vpn_gateway_interface           = 1<br>          peer_external_gateway_interface = 1<br>          shared_secret                   = "secret"<br>        }<br>      }<br>    }<br>  }<br>}</pre> | `any` | n/a | yes |
 | <a name="input_vpn_gateway_name"></a> [vpn\_gateway\_name](#input\_vpn\_gateway\_name) | VPN gateway name. Gateway created by the module | `string` | n/a | yes |