Add release notes

Author: cowtowncoder

release-notes/CREDITS

@@ -23,3 +23,8 @@ Andy Wilkinson (@wilkinsona)
 * Requested #619: (avro, cbor, ion, smile) Add `isEnabled()` methods for format-specific features
   (like `CBORReadFeature` and `CBORWriteFeature`) to mappers
  (3.1.0)
+
+Michael Liedtke (@mcliedtke)
+
+* Contributed #629: (ion) Unnecessary `IOException` in `IonObjectMapper` method signatures
+ (3.1.0)

release-notes/VERSION

@@ -23,6 +23,8 @@ implementations)
  (requested by Andy W)
 #623: (ion) Upgrade `ion-java` dep to 1.11.11 (from 1.11.10)
  (requested by @Shaurya0108)
+#629: (ion) Unnecessary `IOException` in `IonObjectMapper` method signatures
+ (fix contributed by Michael L)
 
 3.0.1 (21-Oct-2025)