making documentation for national clouds more clear

Author: Matthew Henderson

articles/app-service/configure-authentication-provider-aad.md

@@ -95,7 +95,7 @@ Perform the following steps:
     |Field|Description|
     |-|-|
     |Client ID| Use the **Application (client) ID** of the app registration. |
-    |Issuer Url| Use `https://login.microsoftonline.com/<tenant-id>/v2.0`, and replace *\<tenant-id>* with the **Directory (tenant) ID** of the app registration. This value is used to redirect users to the correct Azure AD tenant, as well as to download the appropriate metadata to determine the appropriate token signing keys and token issuer claim value for example. The `/v2.0` section may be omitted for applications using AAD v1. |
+    |Issuer Url| Use `<authentication-endpoint>/<tenant-id>/v2.0`, and replace *\<authentication-endpoint>* with the [authentication endpoint for your cloud environment](../active-directory/develop/authentication-national-cloud.md#azure-ad-authentication-endpoints) (e.g., "https://login.microsoft.com" for global Azure), also replacing *\<tenant-id>* with the **Directory (tenant) ID** in which the app registration was created. This value is used to redirect users to the correct Azure AD tenant, as well as to download the appropriate metadata to determine the appropriate token signing keys and token issuer claim value for example. The `/v2.0` section may be omitted for applications using AAD v1. |
     |Client Secret (Optional)| Use the client secret you generated in the app registration.|
     |Allowed Token Audiences| If this is a cloud or server app and you want to allow authentication tokens from a web app, add the **Application ID URI** of the web app here. The configured **Client ID** is *always* implicitly considered to be an allowed audience. |