add comment for kotlin version

Author: oshai

gradle/libs.versions.toml

@@ -1,5 +1,7 @@
 [versions]
 
+# kotlin version > 2.1.x do not support kotlin 2.0 competability
+# see https://github.com/oshai/kotlin-logging/issues/546
 kotlin = "2.1.21"
 android-gradle-plugin = "8.12.0"
 dokka = "2.0.0"