website: update to 1.5 on homepage link (#5817)

website/source/index.html.erb

@@ -12,7 +12,7 @@ description: |-
         <div>
           <div>
             <a class='notification' href='/downloads.html'>
-              <span>New</span> HashiCorp Consul 1.4 has been released! Download now <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>
+              <span>New</span> HashiCorp Consul 1.5 has been released! Download now <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>Service Mesh Made Easy</h1>
             <p>Consul is a distributed service mesh to connect, secure, and configure services across any runtime platform and public or private cloud</p>