Use new Language stub for samples (Azure#30013)

Author: heaths

sdk/cognitivelanguage/Azure.AI.Language.Conversations/samples/README.md

@@ -6,6 +6,7 @@ products:
 - azure
 - azure-cognitive-services
 - azure-language-understanding
+- language-service
 name: Azure.AI.Language.Conversations samples for .NET
 description: Samples for the Azure.AI.Language.Conversations client library
 ---

sdk/cognitivelanguage/Azure.AI.Language.QuestionAnswering/samples/README.md

@@ -6,6 +6,7 @@ products:
 - azure
 - azure-cognitive-services
 - azure-qna-maker
+- language-service
 name: Azure.AI.Language.QuestionAnswering samples for .NET
 description: Samples for the Azure.AI.Language.QuestionAnswering client library
 ---

sdk/textanalytics/Azure.AI.TextAnalytics/samples/README.md

@@ -6,6 +6,7 @@ products:
 - azure
 - azure-cognitive-services
 - azure-text-analytics
+- language-service
 name: Azure Text Analytics samples for .NET
 description: Samples for the Azure.AI.TextAnalytics client library
 ---