Add ability to show a help text under the search box

Author: mshibuya

app/views/rails_admin/main/index.html.erb

@@ -83,6 +83,9 @@
               <i class="fas fa-times"></i>
             </button>
           </div>
+          <% if @model_config.list.search_help.present? %>
+            <div class="form-text"><%= @model_config.list.search_help %></div>
+          <% end %>
         </div>
         <div class="col-sm-6 text-end">
           <% if export_action %>

lib/rails_admin/config/sections/list.rb

@@ -30,6 +30,10 @@ class List < RailsAdmin::Config::Sections::Base
           nil
         end
 
+        register_instance_option :search_help do
+          nil
+        end
+
         register_instance_option :sort_by do
           parent.abstract_model.primary_key
         end

spec/integration/actions/index_spec.rb

@@ -321,6 +321,16 @@
         },
       ]
     end
+
+    it 'shows the help text below the search box' do
+      RailsAdmin.config Player do
+        list do
+          search_help 'Use this box to search!'
+        end
+      end
+      visit index_path(model_name: 'player')
+      is_expected.to have_css('.form-text', text: /Use this box/)
+    end
   end
 
   describe 'fields' do