Improve description of spring.datasource.initialization-mode

Closes gh-21121

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceProperties.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -94,7 +94,8 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	private String jndiName;
 
 	/**
-	 * Initialize the datasource with available DDL and DML scripts.
+	 * Mode to apply when determining if DataSource initialization should be performed
+	 * using the available DDL and DML scripts.
 	 */
 	private DataSourceInitializationMode initializationMode = DataSourceInitializationMode.EMBEDDED;