Update B.1. Meta-data format.md

Author: qibaoguang

X. Appendices/B.1. Meta-data format.md

@@ -7,6 +7,12 @@
         "name": "server",
         "type": "org.springframework.boot.autoconfigure.web.ServerProperties",
         "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
+    },
+    {
+        "name": "spring.jpa.hibernate",
+        "type": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate",
+        "sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties",
+        "sourceMethod": "getHibernate()"
     }
     ...
 ],"properties": [
@@ -18,10 +24,42 @@
     {
         "name": "server.servlet-path",
         "type": "java.lang.String",
-        "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
+        "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties",
         "defaultValue": "/"
+    },
+    {
+          "name": "spring.jpa.hibernate.ddl-auto",
+          "type": "java.lang.String",
+          "description": "DDL mode. This is actually a shortcut for the \"hibernate.hbm2ddl.auto\" property.",
+          "sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate"
     }
     ...
+],"hints": [
+    {
+        "name": "spring.jpa.hibernate.ddl-auto",
+        "values": [
+            {
+                "value": "none",
+                "description": "Disable DDL handling."
+            },
+            {
+                "value": "validate",
+                "description": "Validate the schema, make no changes to the database."
+            },
+            {
+                "value": "update",
+                "description": "Update the schema if necessary."
+            },
+            {
+                "value": "create",
+                "description": "Create the schema and destroy previous data."
+            },
+            {
+                "value": "create-drop",
+                "description": "Create and then destroy the schema at the end of the session."
+            }
+        ]
+    }
 ]}
 ```
 每个"property"是一个配置节点，用户可以使用特定的值指定它。例如，`server.port`和`server.servlet-path`可能在`application.properties`中如以下定义：