docs: fix wrong link

yanglbme · yanglbme · commit 74209ac65bfc · 2019-02-25T16:41:31.000+08:00
diff --git a/README.md b/README.md
@@ -3,6 +3,7 @@
 [![original](https://badgen.net/badge/original/%E4%B8%AD%E5%8D%8E%E7%9F%B3%E6%9D%89/orange)](https://github.com/doocs/advanced-java)
 [![stars](https://badgen.net/github/stars/doocs/advanced-java)](https://github.com/doocs/advanced-java/stargazers)
 [![forks](https://badgen.net/github/forks/doocs/advanced-java)](https://github.com/doocs/advanced-java/network/members)
+[![help-wanted](https://badgen.net/github/label-issues/doocs/advanced-java/help%20wanted/open)](https://github.com/doocs/advanced-java/labels/help%20wanted)
 [![issues](https://badgen.net/github/open-issues/doocs/advanced-java)](https://github.com/doocs/advanced-java/issues)
 [![PRs Welcome](https://badgen.net/badge/PRs/welcome/green)](http://makeapullrequest.com)
 
