Optimize code and resources

Author: wenlng

README.md

@@ -19,13 +19,10 @@ Package captcha implements generation and click location verification of image C
 <br/>
 
 <div align="center">
-    <img src="http://47.104.180.148/go-captcha/go-captcha-01.png?v=2" alt="Reward Support">
+    <img src="http://47.104.180.148/go-captcha/go-captcha-01.png?v=4" alt="Reward Support">
     <br/>
-    <br/>
-    <img src="http://47.104.180.148/go-captcha/go-captcha-02.png?v=1" alt="Reward Support">
-    <br/>
-    <br/>
-    <img src="http://47.104.180.148/go-captcha/go-captcha.jpg?v=1" alt="Reward Support">
+    <br/> 
+    <img src="http://47.104.180.148/go-captcha/go-captcha.jpg?v=4" alt="Reward Support">
     <br/>
     <br/>   
 </div>

README_zh.md

@@ -19,15 +19,12 @@ go-captcha, 一个简洁易用、交互友好、高安全性的"行为式验证
 <br/>
 
 <div align="center">
-    <img src="http://47.104.180.148/go-captcha/go-captcha-01.png?v=2" alt="Reward Support">
+    <img src="http://47.104.180.148/go-captcha/go-captcha-01.png?v=4" alt="Reward Support">
     <br/>
+    <br/> 
+    <img src="http://47.104.180.148/go-captcha/go-captcha.jpg?v=4" alt="Reward Support">
     <br/>
-    <img src="http://47.104.180.148/go-captcha/go-captcha-02.png?v=1" alt="Reward Support">
     <br/>
-    <br/>
-    <img src="http://47.104.180.148/go-captcha/go-captcha.jpg?v=1" alt="Reward Support">
-    <br/>
-    <br/>   
 </div>
 
 ## 中国Go模块代理