Rename Riot to Element.

Riot was recently renamed to Element,
as described in this blog post:
https://element.io/blog/welcome-to-element/

This commit updates the product page for
Hosted Matrix to use the new name.

content/u/products/hosted-matrix-chat/contents.lr

@@ -132,11 +132,11 @@ description3:
 
       <p>There are <a href="https://matrix.org/clients/">many Matrix
         clients</a>, although we <b>strongly recommend</b> <a
-        href="https://about.riot.im/features">Riot</a> which is the most
+        href="https://element.io/features">Element</a> which is the most
       advanced at the moment. Be aware, however, that you might be a bit
       confused with its UI/UX at first (there is ongoing work to improve
-      onboarding): we encourage you to <a href="https://riot.im/app/">try
-      Riot/Matrix</a> first if your are not already familiar with it.
+      onboarding): we encourage you to <a href="https://app.element.io/">try
+      Element/Matrix</a> first if your are not already familiar with it.
       </p>
 
     </div>