Added mandatory role detail to be able to do this quickstart tutorial successfully

Author: boletus151

articles/ai-services/language-service/custom-text-classification/includes/quickstarts/language-studio.md

@@ -23,6 +23,8 @@ Before you can use custom text classification, you'll need to create an Azure AI
 > To quickly get started, we recommend creating a new Azure AI Language resource using the steps provided in this article. Using the steps in this article will let you create the Language resource and storage account at the same time, which is easier than doing it later.
 >
 > If you have a [pre-existing resource](../../how-to/create-project.md#using-a-pre-existing-language-resource) that you'd like to use, you will need to connect it to storage account.
+>
+> Adding the role **Storage Blob Data Contributor** is essential for interacting with *any resource* that utilizes the storage account
 
 [!INCLUDE [create a new resource from the Azure portal](../resource-creation-azure-portal.md)]