typo fixed: json readme.md, add ":" for debug type

wayslog · wayslog · commit 8ad866b15c17 · 2016-05-13T17:03:37.000+08:00
diff --git a/action/json_data/readme.md b/action/json_data/readme.md
@@ -148,7 +148,7 @@ fn main() {
     // Deserialize using `json::decode`
     // 将json字符串中的数据转化成TestStruct对应的数据，相当于初始化
     let decoded: TestStruct = json::decode(&encoded).unwrap();
-    println!("{?}",decoded.data_vector);
+    println!("{:?}",decoded.data_vector);
 }
 
 ```

Original file line number	Diff line number	Diff line change
`@@ -148,7 +148,7 @@ fn main() {`
`148`	`148`	// Deserialize using `json::decode`
`149`	`149`	`// 将json字符串中的数据转化成TestStruct对应的数据，相当于初始化`
`150`	`150`	`let decoded: TestStruct = json::decode(&encoded).unwrap();`
`151`		`- println!("{?}",decoded.data_vector);`
	`151`	`+ println!("{:?}",decoded.data_vector);`
`152`	`152`	`}`
`153`	`153`
`154`	`154`	```