Use versions.doc url for the hero link on the landing page

Author: rozza

docs/landing/layouts/partials/hero.html

@@ -8,7 +8,9 @@ <h2>MongoDB Java Driver</h2>
         The next generation Java driver for MongoDB
       </p>
       <p>
-      <a href="{{.Site.BaseUrl}}/{{$.Site.Data.releases.current}}" class="btn btn-success btn-dark btn-mongo">Latest documentation</a>
+        {{ range where $.Site.Data.releases.versions "version" $.Site.Data.releases.current  }}{{ $.Scratch.Set "qs.currentReleasedVersion" . }}{{end }}
+        {{$currentReleasedVersion := $.Scratch.Get "qs.currentReleasedVersion"}}
+      <a href="{{$currentReleasedVersion.docs}}" class="btn btn-success btn-dark btn-mongo">Latest documentation</a>
       </p>
 
     </div>