SCALA-55: add link in README

Author: KevinGilmore

scala-lang/README.md

@@ -2,4 +2,5 @@
 
 This module contains articles about Scala's Lang features 
 
-- [Def, Var & Val in Scala](https://www.baeldung.com/scala/def-var-val)
+- [Def, Var & Val in Scala](https://www.baeldung.com/scala/def-var-val)
+- [Difference Between Class and Case Class in Scala](https://www.baeldung.com/scala/case-class)