Removed references to deprecated service, Azure Spatial Anchors (Azure#48039)

Author: pamistel

sdk/mixedreality/Azure.MixedReality.Authentication/README.md

@@ -1,13 +1,11 @@
 # Azure Mixed Reality Authentication client library for .NET
 
-Mixed Reality services, like Azure Spatial Anchors, Azure Remote Rendering, and others, use the Mixed Reality security
+Mixed Reality services, like Azure Remote Rendering, use the Mixed Reality security
 token service (STS) for authentication. This package supports exchanging Mixed Reality account credentials for an access
 token from the STS that can be used to access Mixed Reality services.
 
 [Source code](https://github.com/Azure/azure-sdk-for-net/tree/main/sdk/mixedreality/Azure.MixedReality.Authentication/src) | [Package (NuGet)](https://www.nuget.org/packages/Azure.MixedReality.Authentication)
 
-![Mixed Reality service authentication diagram](https://learn.microsoft.com/azure/spatial-anchors/concepts/media/spatial-anchors-authentication-overview.png)
-
 - [Azure Mixed Reality Authentication client library for .NET](#azure-mixed-reality-authentication-client-library-for-net)
   - [Getting started](#getting-started)
     - [Install the package](#install-the-package)
@@ -51,7 +49,6 @@ Add a package reference:
 - You must have an [Azure subscription](https://azure.microsoft.com/free/dotnet/).
 - You must have an account with an [Azure Mixed Reality service](https://azure.microsoft.com/topic/mixed-reality/):
   - [Azure Remote Rendering](https://learn.microsoft.com/azure/remote-rendering/)
-  - [Azure Spatial Anchors](https://learn.microsoft.com/azure/spatial-anchors/)
 - Familiarity with the authentication and credential concepts from [Azure.Identity](https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/identity/Azure.Identity/README.md).
 
 ### Authenticate the client
@@ -69,8 +66,6 @@ Mixed Reality services support a few different forms of authentication:
     method for production applications because it allows you to avoid embedding the credentials for access to a Mixed
     Reality service in your client application.
 
-See [here](https://learn.microsoft.com/azure/spatial-anchors/concepts/authentication) for detailed instructions and information.
-
 #### Authentication examples
 
 Below are some examples of some common authentication scenarios, but more examples and information can be found at

sdk/mixedreality/Azure.ResourceManager.MixedReality/README.md

@@ -1,6 +1,6 @@
 # Microsoft Azure Mixed Reality management client library for .NET
 
-Microsoft Azure Mixed Reality cloud services like Azure Remote Rendering and Azure Spatial Anchors help developers build compelling immersive experiences on a variety of platforms. These services allow you to integrate spatial awareness into your projects when you're making applications for 3D training, predictive equipment maintenance, and design review, all in the context of your users’ environments.
+Microsoft Azure Mixed Reality cloud services like Azure Remote Rendering help developers build compelling immersive experiences on a variety of platforms.
 
 This library supports managing Microsoft Azure Mixed Reality resources.