Update _previewpage

Author: vikram-redhat

scripts/ocpdocs/_previewpage

@@ -42,6 +42,18 @@
 
                             </div>
                         </div>
+                        <div class="col-sm-3 text-center">
+                            <h2>OpenShift ROSA</h2>
+                            <div class="list-group">
+                                <p>
+                                    <a role="button" class="btn btn-primary" href="/openshift-rosa/latest/welcome/index.html">
+                                        <i class="fa fa-arrow-circle-o-right"></i> ROSA</a>
+                                </p>
+                                <p class="list-group-item-text">Managed OpenShift in the AWS cloud.</p>
+
+                            </div>
+                        </div>
+                        
                     </div>
                 </div>
             </div>