Removed the preview references from the article (SharePoint#6444)

Azure Multi-Stage pipelines are now generally available

Author: rifaj

docs/spfx/toolchain/implement-ci-cd-with-azure-pipelines.md

@@ -1,5 +1,5 @@
 ---
-title: Implement Continuous Integration and Continuous deployment using Azure Pipelines (preview)
+title: Implement Continuous Integration and Continuous deployment using Azure Pipelines
 description: Streamlining the build and deployment process by automating manual steps.
 ms.date: 09/07/2020
 ms.prod: sharepoint
@@ -10,15 +10,12 @@ Azure Pipelines is the newer version of the Azure DevOps build and release featu
 
 This article explains the steps involved in setting up your Azure Pipelines environment with Continuous Integration and Continuous Deployment to automate your SharePoint Framework builds, unit tests, and deployment.  
 
-> [!NOTE]
-> Azure Multi-stage Pipelines is still in preview and you need to make sure you [enable this preview feature](https://docs.microsoft.com/azure/devops/project/navigation/preview-features) for your Azure DevOps organization under __Preview Features__.
-
-## Choosing between Azure Multi-stage Pipelines (preview) and Azure DevOps builds and releases
+## Choosing between Azure Multi-stage Pipelines and Azure DevOps builds and releases
 
 There are currently two approaches available to implement continuous integration, and deployment in Azure DevOps.  
 Azure builds and releases is the historic one, featuring a graphical edition experience and storing the definitions in a JSON document hidden from the user.  
 
-Azure multi-stage Pipelines is a newer feature still in preview, is relies on pipeline definitions stored as YAML files on the repository providing transparency, version history, and repeatability.  
+Azure multi-stage Pipelines relies on pipeline definitions stored as YAML files on the repository providing transparency, version history, and repeatability.  
 Both approaches are described for the SharePoint Framework:
 
 - [Azure Build and Release](./implement-ci-cd-with-azure-devops.md)