update doc

doc/QUESTIONS.md

@@ -26,7 +26,7 @@ Check your signature please.
 There's no need to override `AppDelegate` since `fluwx 1.0.0`. If you have did thad before, please remove 
 the following code in your `AppDelegate`:
 
-```
+```objective-c
 
 - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
   return [WXApi handleOpenURL:url delegate:[FluwxResponseHandler defaultManager]];
@@ -38,7 +38,7 @@ the following code in your `AppDelegate`:
 ```
 
 If you have to override these two functions,make sure you have called the `super`:
-```
+```objective-c
 
 - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
     

doc/QUESTIONS_CN.md

@@ -38,7 +38,7 @@ iOS 9系统策略更新，限制了http协议的访问，此外应用需要在
 
 从`fluwx 1.0.0`开始开发者不必重写`AppDelegate`了。如果你以前重写了这个方法,请在 `AppDelegate`中删除相应的代码:
 
-```
+```objective-c
 
 - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
   return [WXApi handleOpenURL:url delegate:[FluwxResponseHandler defaultManager]];
@@ -50,7 +50,7 @@ iOS 9系统策略更新，限制了http协议的访问，此外应用需要在
 ```
 
 如果一定要重写这2个方法,请确保你调用了 `super`:
-```
+```objective-c
 
 - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {