Add comment explaining twin patch over edge isn't applied immediately (…

…#3331)

iothub/device/src/IotHubBaseClient.cs

@@ -447,7 +447,14 @@ public async Task<TwinProperties> GetTwinPropertiesAsync(CancellationToken cance
         /// Push reported property changes up to the service.
         /// </summary>
         /// <remarks>
+        /// <para>
         /// The client instance must be already open.
+        /// </para>
+        /// <para>
+        /// For clients communicating with IoT hub via IoT Edge, since the patch isn't applied immediately an updated version number is not returned.
+        /// You can call <see cref="GetTwinPropertiesAsync(CancellationToken)"/> and verify <see cref="PropertyCollection.Version"/>
+        /// from <see cref="TwinProperties.Reported"/> to check if your patch is successfully applied.
+        /// </para>
         /// </remarks>
         /// <param name="reportedProperties">Reported properties to push</param>
         /// <param name="cancellationToken">A cancellation token to cancel the operation.</param>