add link to 16.x (#295)

Author: munierujp

source/layout/index.njk

@@ -11,6 +11,7 @@
 
 <ul>
   <li><a href="https://nodejs.org/api/">Node.js 最新</a>
+  <li><a href="https://nodejs.org/dist/latest-v16.x/docs/api/">Node.js v16.x</a>
   <li><a href="https://nodejs.org/dist/latest-v14.x/docs/api/">Node.js v14.x</a>
   <li><a href="https://nodejs.org/dist/latest-v12.x/docs/api/">Node.js v12.x</a>
   <li><a href="https://nodejs.org/dist/latest-v10.x/docs/api/">Node.js v10.x</a>