Update README.md

Author: rcalago

core-kotlin-modules/core-kotlin-io/README.md

@@ -8,3 +8,4 @@ This module contains articles about core Kotlin I/O.
 - [Reading from a File in Kotlin](https://www.baeldung.com/kotlin/read-file)
 - [Writing to a File in Kotlin](https://www.baeldung.com/kotlin/write-file)
 - [Writing InputStream to File in Kotlin](https://www.baeldung.com/kotlin/inputstream-to-file)
+- [Rename a File in Kotlin](https://www.baeldung.com/kotlin/file-rename)