website: alert for kubecon (#6806)

* website: alert for kubecon

* Update website/source/index.html.erb

website/source/index.html.erb

@@ -10,6 +10,9 @@ description: |-
       <div>
         <div>
           <div>
+          <a class='notification' href='https://learn.hashicorp.com/consul?track=kubernetes&utm_source=consul.io&utm_medium=banner&utm_term=track#kubernetes'>
+            <span>KUBECON</span> Learn how to deploy Consul on Kubernetes <span><svg xmlns='http://www.w3.org/2000/svg' width='6' height='10' viewBox='0 0 6 10'><path fill='#650D34' d='M1.138.529a.666.666 0 1 0-.942.943L3.724 5 .195 8.53a.666.666 0 1 0 .943.943l4-4a.666.666 0 0 0 0-.943l-4-4z'/></svg><span>
+          </a>
             <h1 class='g-type-display-1'>Secure Service Networking</h1>
             <p  class='g-type-body-large'>Consul is a service networking solution to connect and secure services across any runtime platform and public or private cloud</p>
             <a href='/downloads.html' class='button download'>