Update README.md

Author: Jim Crowley

README.md

@@ -21,7 +21,9 @@ This repository shows you how to access multiple resources, including Microsoft
 
 In addition, the sample uses the [Microsoft Authentication Library (MSAL)](https://www.nuget.org/packages/Microsoft.Identity.Client/) for authentication. The MSAL SDK provides features for working with the [Azure AD v2.0 endpoint](https://msdn.microsoft.com/en-us/office/office365/howto/authenticate-Office-365-APIs-using-v2), which enables developers to write a single code flow that handles authentication for both users' work or school (Azure Active Directory)  or personal (Microsoft) accounts.
 
- > **Note** The MSAL SDK is currently in prerelease, and as such should not be used in production code. It is used here for illustrative purposes only.
+## Important Note about the MSAL Preview
+
+This library is suitable for use in a production environment. We provide the same production level support for this library as we do our current production libraries. During the preview we may make changes to the API, internal cache format, and other mechanisms of this library, which you will be required to take along with bug fixes or feature improvements. This may impact your application. For instance, a change to the cache format may impact your users, such as requiring them to sign in again. An API change may require you to update your code. When we provide the General Availability release we will require you to update to the General Availability version within six months, as applications written using a preview version of library may no longer work.
 
 These snippets are simple and self-contained, and you can copy and paste them into your own code, whenever appropriate, or use them as a resource for learning how to use the Microsoft Graph client library.