Update README.md

[skip ci]

Author: edizor

zio/README.md

@@ -4,3 +4,4 @@
 - [Introduction to ZIO Streams](https://www.baeldung.com/scala/zio-streams-intro)
 - [Resource Handling in ZIO](https://www.baeldung.com/scala/zio-resource-handling)
 - [Different Ways to Create ZIO Effects](https://www.baeldung.com/scala/zio-effects)
+- [Testing ZIO Applications Using ZIO Test](https://www.baeldung.com/scala/zio-test)