Fixes MicrosoftDocs/azure-docs#48951 - Add RP registration step

Author: DCtheGeek

articles/governance/blueprints/create-blueprint-rest-api.md

@@ -1,7 +1,7 @@
 ---
 title: "Quickstart: Create a blueprint with REST API"
 description: In this quickstart, you use Azure Blueprints to create, define, and deploy artifacts using the REST API.
-ms.date: 11/21/2019
+ms.date: 02/26/2020
 ms.topic: quickstart
 ---
 # Quickstart: Define and Assign an Azure Blueprint with REST API
@@ -13,8 +13,10 @@ tasks related to creating, publishing, and assigning a blueprint within your org
 
 ## Prerequisites
 
-If you don't have an Azure subscription, create a [free account](https://azure.microsoft.com/free)
-before you begin.
+- If you don't have an Azure subscription, create a
+  [free account](https://azure.microsoft.com/free) before you begin.
+- Register the `Microsoft.Blueprint` resource provider. For directions, see
+  [Resource providers and types](../../azure-resource-manager/management/resource-providers-and-types.md).
 
 [!INCLUDE [cloud-shell-try-it.md](../../../includes/cloud-shell-try-it.md)]