Add protocol to support TLS between gateway and apps

Author: ninpan-ms

articles/spring-apps/how-to-use-enterprise-spring-cloud-gateway.md

@@ -125,6 +125,7 @@ The route config definition includes the following parts:
 
 - OpenAPI URI: The URI points to an OpenAPI specification. Both OpenAPI 2.0 and OpenAPI 3.0 specs are supported. The specification can be shown in API portal to try out. Two types of URI are accepted. The first type of URI is a public endpoint like `https://petstore3.swagger.io/api/v3/openapi.json`. The second type of URI is a constructed URL `http://<app-name>/{relative-path-to-OpenAPI-spec}`, where `app-name` is the name of an application in Azure Spring Apps that includes the API definition.
 - routes: A list of route rules about how the traffic goes to one app.
+- protocol: The backend protocol of app which gateway routes traffic to. The supported value of it is `HTTP` or `HTTPS`, and the default value is `HTTP`. To secure traffic from gateway to applications that support HTTPS, you need to set protocol to `HTTPS` in the route config.
 
 Use the following command to create a route config. The `--app-name` value should be the name of an app hosted in Azure Spring Apps that the requests will route to.
 
@@ -142,6 +143,7 @@ Here's a sample of the JSON file that is passed to the `--routes-file` parameter
    "open_api": {
       "uri": "<OpenAPI-URI>"
    },
+   "protocol": "<protocol-of-routed-app>",
    "routes": [
       {
          "title": "<title-of-route>",
@@ -224,6 +226,7 @@ Use the following steps to create an example application using Spring Cloud Gate
 
    ```json
    {
+      "protocol": "HTTP",
       "routes": [
          {
             "title": "Customers service",