HHH-14019 Adding some comments to the new SPI

hibernate-core/src/main/java/org/hibernate/tool/schema/spi/SchemaManagementTool.java

@@ -23,5 +23,13 @@ public interface SchemaManagementTool extends Service {
 	SchemaDropper getSchemaDropper(Map options);
 	SchemaMigrator getSchemaMigrator(Map options);
 	SchemaValidator getSchemaValidator(Map options);
+
+	/**
+	 * This allows to set an alternative implementation for the Database
+	 * generation target.
+	 * Used by Hibernate Reactive so that it can use the reactive database
+	 * access rather than needing a JDBC connection.
+	 * @param generationTarget the custom instance to use.
+	 */
 	void setCustomDatabaseGenerationTarget(GenerationTarget generationTarget);
 }