website: add 1.7.0 Beta announcement to Downloads page (#6911)

* website: add 1.7.0 Beta announcement to Downloads page

* Update downloads.html.erb

website/source/downloads.html.erb

@@ -8,6 +8,12 @@ description: |-
 
 <h1>Download Consul</h1>
 
+<div class="alert alert-info" id="beta-1-7" role="alert">
+  <p><strong>1.7.0 Beta Available:</strong> Read more about the new features coming in 1.7.0 in the
+  <a href="https://www.hashicorp.com/blog/announcing-hashicorp-consul-1-7/">announcement post</a>. Binaries can be accessed on <a href="https://releases.hashicorp.com/consul/">releases.hashicorp.com</a>.
+  </p>
+</div>
+
 <section class="downloads">
   <div class="description row">
     <div class="col-md-12">