Update README.md

Author: dragen1860

README.md

@@ -3,7 +3,7 @@
 **课程链接:** https://study.163.com/provider/480000001847407/index.htm?share=2&shareId=480000001847407
 
 
-![](res/cover.png =250x)
+![](./res/cover.png =250x)
 
 **课程大纲:**
 ![课程介绍](res/outline.png)