Add license scan badge (docsifyjs#176)

Author: michellebrier

README.md

@@ -12,6 +12,7 @@
   <a href="https://travis-ci.org/QingWei-Li/docsify"><img alt="Travis Status" src="https://img.shields.io/travis/QingWei-Li/docsify/master.svg?style=flat-square"></a>
   <a href="https://www.npmjs.com/package/docsify"><img alt="npm" src="https://img.shields.io/npm/v/docsify.svg?style=flat-square"></a>
   <a href="https://github.com/QingWei-Li/donate"><img alt="donate" src="https://img.shields.io/badge/%24-donate-ff69b4.svg?style=flat-square"></a>
+  <a href="https://app.fossa.io/projects/git%2Bhttps%3A%2F%2Fgithub.com%2FQingWei-Li%2Fdocsify?ref=badge_shield" alt="FOSSA Status"><img src="https://app.fossa.io/api/projects/git%2Bhttps%3A%2F%2Fgithub.com%2FQingWei-Li%2Fdocsify.svg?type=shield"/></a>
 </p>
 
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