Add missing Javadoc @since tag.
diff --git a/src/main/java/org/apache/commons/text/numbers/DoubleFormat.java b/src/main/java/org/apache/commons/text/numbers/DoubleFormat.java
index 5f2204a..3cc1cb9 100644
--- a/src/main/java/org/apache/commons/text/numbers/DoubleFormat.java
+++ b/src/main/java/org/apache/commons/text/numbers/DoubleFormat.java
@@ -79,6 +79,8 @@
  * <p>{@link java.math.RoundingMode#HALF_EVEN Half-even} rounding is used in cases where the
  * decimal value must be rounded in order to meet the configuration requirements of the formatter
  * instance.
+ *
+ * @since 1.10.0
  */
 public enum DoubleFormat {