Provide Microsoft.AspNetCore.Authentication.MicrosoftAccount package README (#57808)

Author: MackinnonBuck

src/Security/Authentication/MicrosoftAccount/src/PACKAGE.md

@@ -0,0 +1,42 @@
+## About
+
+`Microsoft.AspNetCore.Authentication.MicrosoftAccount` provides ASP.NET Core middleware that enables applications to support the Microsoft Account authentication workflow.
+
+## How to Use
+
+To use `Microsoft.AspNetCore.Authentication.MicrosoftAccount`, follow these steps:
+
+### Installation
+
+```shell
+dotnet add package Microsoft.AspNetCore.Authentication.MicrosoftAccount
+```
+
+### Configuration
+
+1. Refer to the guide in the official documentation [here](https://learn.microsoft.com/aspnet/core/security/authentication/social/microsoft-logins#create-the-app-in-microsoft-developer-portal) to create the app in Microsoft Developer Portal
+2. Follow the steps in the official documentation [here](https://learn.microsoft.com/aspnet/core/security/authentication/social/microsoft-logins#store-the-microsoft-client-id-and-secret) to store the Microsoft client ID and secret
+3. Add the Authentication service to your app's `Program.cs`:
+    ```csharp
+    var builder = WebApplication.CreateBuilder(args);
+
+    builder.Services.AddAuthentication().AddMicrosoftAccount(microsoftOptions =>
+    {
+        microsoftOptions.ClientId = builder.Configuration["Authentication:Microsoft:ClientId"];
+        microsoftOptions.ClientSecret = builder.Configuration["Authentication:Microsoft:ClientSecret"];
+    });
+    ```
+
+## Main Types
+
+The main types provided by this package are:
+* `MicrosoftAccountOptions`: Represents the options for configuring Microsoft Account authentication
+* `MicrosoftAccountHandler`: The authentication handler responsible for processing Microsoft Account authentication requests and generating the appropriate authentication ticket
+
+## Additional Documentation
+
+For additional documentation and examples, refer to the [official documentation](https://learn.microsoft.com/aspnet/core/security/authentication/social/microsoft-logins) on Microsoft Account login setup in ASP.NET Core.
+
+## Feedback & Contributing
+
+`Microsoft.AspNetCore.Authentication.MicrosoftAccount` is released as open-source under the [MIT license](https://licenses.nuget.org/MIT). Bug reports and contributions are welcome at [the GitHub repository](https://github.com/dotnet/aspnetcore).