Update configuration.xml

Delete redundant content

Author: vincenthsin

src/site/xdoc/configuration.xml

@@ -1409,10 +1409,6 @@ public class GenericTypeHandler<E extends MyObject> extends BaseTypeHandler<E> {
     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
-<!DOCTYPE mapper
-    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
-    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
-
 <mapper namespace="org.apache.ibatis.submitted.rounding.Mapper">
     <resultMap type="org.apache.ibatis.submitted.rounding.User" id="usermap">
         <id column="id" property="id"/>