Update README.md

Author: JeffLi1993

README.md

@@ -8,7 +8,7 @@ spring boot 实践学习案例，是 spring boot 初学者及核心技术巩固
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+              <img width="300" src="http://www.bysocket.com/wp-content/uploads/2019/03/911551666328_.pic_hd.jpg">
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