OSSM-6940: Update _previewpage to include Service Mesh

Author: rh-tokeefe

scripts/ocpdocs/_previewpage

@@ -221,6 +221,23 @@
               </p>
             </div>
           </div>
+          <div class="col-sm-6 text-center">
+            <h2>OpenShift Service Mesh</h2>
+            <div class="list-group">
+              <p>
+                <a
+                  role="button"
+                  class="btn btn-primary"
+                  href="/openshift-service-mesh/latest/welcome/index.html"
+                >
+                  <i class="fa fa-arrow-circle-o-right"></i> Service Mesh</a
+                >
+              </p>
+              <p class="list-group-item-text">
+                OpenShift Service Mesh documentation.
+              </p>
+            </div>
+          </div>
         </div>
       </div>
     </div>