Add contest organizer form param

app/views/contests/settings_onsite_edit.html.slim

@@ -1,7 +1,17 @@
 = render "params_nav"
 
 = form_with model: @contest, url: "/contests/#{@contest.id}/settings/onsite" do |form|
-  .row.mt-2.mb-3
+  .row
+    .col
+      .alert.alert-warning role="alert"
+        = t("contests.nav.onsite_description")
+  .row.mt-1
+    .col
+      .form-check.form-switch
+        = form.check_box :organizer_form, class: "form-check-input"
+        = form.label :organizer_form
+      .form-text = t("activerecord.attributes.contest.organizer_form")
+  .row.mt-3.mb-3
     .col
       .form-floating
         = form.text_field :code, autocomplete: "off", class: "form-control"