update readme to use correct production_name (Azure#28607)

Author: kristapratico

sdk/cognitivelanguage/azure-ai-language-questionanswering/README.md

@@ -137,7 +137,7 @@ client = QuestionAnsweringClient(endpoint, AzureKeyCredential(key))
 output = client.get_answers(
     question="How long should my Surface battery last?",
     project_name="FAQ",
-    deployment_name="test"
+    deployment_name="production"
 )
 for candidate in output.answers:
     print("({}) {}".format(candidate.confidence, candidate.answer))
@@ -168,7 +168,7 @@ output = client.get_answers(
         previous_qna_id=previous_answer.qna_id
     ),
     project_name="FAQ",
-    deployment_name="live"
+    deployment_name="production"
 )
 for candidate in output.answers:
     print("({}) {}".format(candidate.confidence, candidate.answer))
@@ -326,7 +326,7 @@ try:
     client.get_answers(
         question="Why?",
         project_name="invalid-knowledge-base",
-        deployment_name="test"
+        deployment_name="production"
     )
 except HttpResponseError as error:
     print("Query failed: {}".format(error.message))