docs: add link to rn-tester's README.md (callstack#5)

Author: thymikee

README.md

@@ -17,4 +17,4 @@ This project is still at an early stage of development and is not ready for prod
 
 1. Download latest Xcode beta [here](https://developer.apple.com/xcode/).
 2. Install VisionOS Simulator runtime. 
-3. Follow the same steps as for running iOS defined in `packages/rn-tester/README.md`
+3. Follow the same steps as for running iOS defined in [packages/rn-tester/README.md](./packages/rn-tester/README.md)