Update ERB file to use error f.error_notification

lib/generators/simple_form/templates/_form.html.erb

@@ -1,15 +1,5 @@
 <%%= simple_form_for(@<%= singular_name %>) do |f| %>
-  <%% if @<%= singular_name %>.errors.any? %>
-    <div id="error_explanation">
-      <h2><%%= pluralize(@<%= singular_name %>.errors.count, "error") %> prohibited this <%= singular_name %> from being saved:</h2>
-
-      <ul>
-      <%% @<%= singular_name %>.errors.full_messages.each do |msg| %>
-        <li><%%= msg %></li>
-      <%% end %>
-      </ul>
-    </div>
-  <%% end %>
+  <%%= f.error_notification %>
 
   <div class="inputs">
   <%- attributes.each do |attribute| -%>