Update README.md (#4667)

README.md

@@ -1,4 +1,4 @@
-# Microsoft Test Framework
+# Microsoft Testing Platform and Microsoft Test Framework
 
 [![GitHub release](https://img.shields.io/github/release/microsoft/testfx.svg)](https://GitHub.com/microsoft/testfx/releases/)
 [![GitHub repo size](https://img.shields.io/github/repo-size/microsoft/testfx)](https://github.com/microsoft/testfx)
@@ -10,6 +10,10 @@
 [![Commit Activity](https://img.shields.io/github/commit-activity/m/microsoft/testfx)](.)
 [![Build Status](https://dev.azure.com/dnceng-public/public/_apis/build/status/Microsoft/testfx/microsoft.testfx?branchName=main)](https://dev.azure.com/dnceng-public/public/_build/latest?definitionId=209&branchName=main)
 
+This repository is the home for Microsoft Testing Platform and extensions, as well as MSTest.
+
+Microsoft Testing Platform is a lightweight alternative to VSTest. For more information, see [Microsoft.Testing.Platform overview](https://learn.microsoft.com/dotnet/core/testing/unit-testing-platform-intro).
+
 MSTest, Microsoft Testing Framework, is a unit testing framework for .NET applications. It allows you to write tests, use Test Explorer, create test suites, and apply the red, green, and refactor patterns to write code.
 
 This is a fully supported, open source, and cross-platform test framework with which to write tests targeting .NET Framework, .NET Core, .NET, UWP, and WinUI on Windows, Linux, and Mac.