Merge branch 'master' into 'master'

update course

See merge request codechina/operation-work!60

explore/index.yml

 banner:
-- link: https://codechina.csdn.net/courses/detail/2/l?utm_source=explore
-  url: https://codechina.csdn.net/codechina/operation-work/uploads/6a42cb09830df2ead3d3d62cde6bc1b5/markdown-banner.jpg
+- link: https://codechina.csdn.net/courses/detail/1/l
+  url: https://codechina.csdn.net/codechina/operation-work/uploads/3d1c29bc9e4003473c6f746c075722cb/Git%E5%9F%BA%E7%A1%80%E5%85%A5%E9%97%A8.jpg
 groups:
 - COPU
 - sureness