Remove Galois sponsorship, add Digital Ocean

As per #340 (comment)

Author: tomjaguarpaw

site/index.html

@@ -498,7 +498,7 @@ <h2>Sponsors</h2>
       </div>
       <div class=" row ">
          <div class=" span6 col-sm-6">
-            <p><strong><a href="https://www.galois.com">Galois</a></strong> provides infrastructure, funds, administrative resources and has historically hosted critical Haskell.org infrastructure, as well as helping the Haskell community at large with their work.</p>
+            <p><strong><a href="https://www.digitalocean.com/">Digital Ocean</a></strong> hosts critical Haskell.org infrastructure.</p>
          </div>
       </div>
    </div>