update README.md.

Signed-off-by: 奔跑的面条 <1262327911@qq.com>

README.md

@@ -157,4 +157,4 @@ setup() {
 
 QQ群: 495755841
 
-<img src="public/QQ2.png" />
+<img src="public/QQ2.png" width="200px"/>