Add related projects to top-level README (#34)

Author: neakor

README.md

@@ -95,6 +95,12 @@ $ swift test
 
 Or you can follow the steps above to generate a Xcode project and run tests within Xcode.
 
+## Related projects
+
+If you like Needle, check out other related open source projects from our team:
+- [Needle](https://github.com/uber/needle): a compile-time safe Swift dependency injection framework.
+- [Swift Abstract Class](https://github.com/uber/swift-abstract-class): a light-weight library along with an executable that enables compile-time safe abstract class development for Swift projects.
+- [Swift Common](https://github.com/uber/swift-common): common libraries used by this set of Swift open source projects.
 
 ## License
 [![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency?ref=badge_large)