Add Swift Testing to Core Libraries

Author: fpseverino

documentation/core-libraries/_swift-testing.md

@@ -0,0 +1,9 @@
+## Swift Testing
+
+Swift Testing is a package with expressive and intuitive APIs that make testing your Swift code a breeze.
+
+It provides detailed output when a test fails using macros like `#expect`. And it scales to large codebases with features like parameterization to easily repeat a test with different arguments.
+
+If you already have tests written using XCTest, you can run them side-by-side with newer tests written using Swift Testing. This helps you migrate tests incrementally, at your own pace.
+
+More information about Swift Testing is available on our [GitHub project page](https://github.com/swiftlang/swift-testing).

documentation/core-libraries/index.md

@@ -25,14 +25,13 @@ have a goal of providing stable and useful features in the following key areas:
 
 These libraries are part of our ongoing work to extend the cross-platform capabilities of Swift.  We chose to make them part of our open source release so that we can work on them together with the community.
 
-Writing code that provides all of this functionality from scratch would be an enormous undertaking. Therefore, we've decided to bootstrap this project by taking advantage of great work that has already been done in these areas. Specifically, we will reuse the API and as much implementation as is possible from three existing libraries: `Foundation`, `libdispatch`, and `XCTest`.
+Writing code that provides all of this functionality from scratch would be an enormous undertaking. Therefore, we've decided to bootstrap this project by taking advantage of great work that has already been done in these areas. Specifically, we will reuse the API and as much implementation as is possible from three existing libraries: `Foundation`, `libdispatch`, and `XCTest`. In addition to these there is `Swift Testing`, a new testing library designed from the ground up for Swift.
 
 * * *
 
 {% include_relative _foundation.md %}
 {% include_relative _libdispatch.md %}
+{% include_relative _swift-testing.md %}
 {% include_relative _xctest.md %}
 
 * * *
-
-As stated above, this project is in its early days. We look forward to working together with the community to create a great set of libraries that enable Swift to produce powerful software across platforms.