Update README.md

Author: johnA1331

core-scala/README.md

@@ -16,3 +16,4 @@ This module contains articles about Scala's core features
 - [A Guide to Sorting in Scala](https://www.baeldung.com/scala/sorting)
 - [An Introduction to Scala Extractor Objects](https://www.baeldung.com/scala/extractor-objects)
 - [A Comprehensive Guide to For-Comprehension in Scala](https://www.baeldung.com/scala/for-comprehension)
+- [Introduction to Traits in Scala](https://www.baeldung.com/scala/traits)