Fix broken chat functions example in README (Azure#38461)

* Fix broken chat functions example in README

The use of the ChatRole.Function message will fail if the message doesn't have its Name set to the name of function.

* Update test as well

Author: stephentoub

sdk/openai/Azure.AI.OpenAI/README.md

@@ -323,7 +323,10 @@ if (responseChoice.FinishReason == CompletionsFinishReason.FunctionCall)
             ChatRole.Function,
             JsonSerializer.Serialize(
                 functionResultData,
-                new JsonSerializerOptions() {  PropertyNamingPolicy = JsonNamingPolicy.CamelCase }));
+                new JsonSerializerOptions() {  PropertyNamingPolicy = JsonNamingPolicy.CamelCase }))
+        {
+            Name = responseChoice.Message.FunctionCall.Name
+        };
         conversationMessages.Add(functionResponseMessage);
         // Now make a new request using all three messages in conversationMessages
     }

sdk/openai/Azure.AI.OpenAI/tests/Samples/Sample07_ChatFunctions.cs

@@ -90,7 +90,10 @@ public async Task ChatFunctions()
                         ChatRole.Function,
                         JsonSerializer.Serialize(
                             functionResultData,
-                            new JsonSerializerOptions() {  PropertyNamingPolicy = JsonNamingPolicy.CamelCase }));
+                            new JsonSerializerOptions() {  PropertyNamingPolicy = JsonNamingPolicy.CamelCase }))
+                    {
+                        Name = responseChoice.Message.FunctionCall.Name
+                    };
                     conversationMessages.Add(functionResponseMessage);
                     // Now make a new request using all three messages in conversationMessages
                 }