Add playground to nav

Author: sergeysova

templates/components/nav.hbs

@@ -11,6 +11,7 @@
   <ul class="nav list w-100 w-auto-l flex flex-none flex-row flex-wrap justify-center justify-end-l items-center pv2 ph0 ph4-ns">
     <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="{{baseurl}}/tools/install">{{fluent "nav-install"}}</a></li>
     <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="{{baseurl}}/learn">{{fluent "nav-learn"}}</a></li>
+    <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="https://play.rust-lang.org/">{{fluent "nav-playground"}}</a></li>
     <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="{{baseurl}}/tools">{{fluent "nav-tools"}}</a></li>
     <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="{{baseurl}}/governance">{{fluent "nav-governance"}}</a></li>
     <li class="tc pv2 ph2 ph4-ns flex-20-s"><a href="{{baseurl}}/community">{{fluent "nav-community"}}</a></li>