Update README-zh.md

Author: yanjinhuagood

README-zh.md

@@ -88,7 +88,7 @@ xmlns:wd="https://github.com/WPFDevelopersOrg/WPFDevelopers"
 ###  第三步：添加命名空间;
 
 
-`xmlns:wpfdev="https://github.com/WPFDevelopersOrg/WPFDevelopers"`  
+`xmlns:wd="https://github.com/WPFDevelopersOrg/WPFDevelopers"`  
 
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