Add Wasm to the list of supported platforms in README.md

Author: kateinoigakukun

README.md

@@ -102,6 +102,7 @@ for various platforms:
 | **visionOS** | | | Supported |
 | **Ubuntu 22.04** | [![Build Status](https://ci.swift.org/buildStatus/icon?job=swift-testing-main-swift-6.0-linux)](https://ci.swift.org/job/swift-testing-main-swift-6.0-linux/) | [![Build Status](https://ci.swift.org/buildStatus/icon?job=swift-testing-main-swift-main-linux)](https://ci.swift.org/view/Swift%20Packages/job/swift-testing-main-swift-main-linux/) | Supported |
 | **Windows** | | [![Build Status](https://ci-external.swift.org/buildStatus/icon?job=swift-testing-main-swift-main-windows)](https://ci-external.swift.org/job/swift-testing-main-swift-main-windows/) | Supported |
+| **Wasm** | | | Experimental |
 
 ### Works with XCTest