[secure] Use mybatis.org directly for secure https

Author: hazendaz

src/site/site.xml

@@ -27,7 +27,7 @@
 
   <bannerRight>
     <name>MyBatis</name>
-    <src>http://mybatis.github.io/images/mybatis-logo.png</src>
+    <src>https://mybatis.org/images/mybatis-logo.png</src>
     <alt>MyBatis logo</alt>
     <href>http://www.mybatis.org/</href>
   </bannerRight>