Add change log entry

Author: kimdv

Release Notes/601.md

@@ -2,8 +2,18 @@
 
 ## New APIs
 
+- `IntegerLiteralExprSyntax` and `FloatLiteralExprSyntax` now have a computed `representedLiteralValue` property.
+  - Description: Allows retrieving the represented literal value when valid.
+  - Issue: https://github.com/apple/swift-syntax/issues/405
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2605
+
 ## API Behavior Changes
 
+- Moved `Radix` and `IntegerLiteralExprSyntax.radix` from `SwiftRefactor` to `SwiftSyntax`.
+  - Description: Allows retrieving the radix value from the `literal.text`.
+  - Issue: https://github.com/apple/swift-syntax/issues/405
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2605
+
 ## Deprecations
 
 ## API-Incompatible Changes