add a note to Javadoc of IdGeneratorType

Signed-off-by: Gavin King <gavin@hibernate.org>

hibernate-core/src/main/java/org/hibernate/annotations/IdGeneratorType.java

@@ -68,6 +68,10 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  * <p>
  * A {@code @IdGeneratorType} annotation must have retention policy
  * {@link RetentionPolicy#RUNTIME}.
+ * <p>
+ * If a {@code Generator} may be used to generate values of non-identifier
+ * fields, its generator annotation should also be meta-annotated
+ * {@link ValueGenerationType @ValueGenerationType}.
  *
  * @see Generator
  * @see AnnotationBasedGenerator

hibernate-core/src/main/java/org/hibernate/annotations/ValueGenerationType.java

@@ -55,7 +55,7 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  * the property to be generated when any SQL statement to {@code insert} or
  * {@code update} the entity is executed.
  * <p>
- * Every generator annotation type has an {@link Generator} implementation
+ * Every generator annotation type has a {@link Generator} implementation
  * which is responsible for generating values. It must be either:
  * <ul>
  * <li>a {@link BeforeExecutionGenerator}, for values that are generated in