set up example scaffold with rspec + factorybot tests

lib/dashboard/engine.rb

@@ -1,5 +1,11 @@
 module Dashboard
   class Engine < ::Rails::Engine
     isolate_namespace Dashboard
+
+    config.generators do |g|
+      g.test_framework :rspec
+      g.fixture_replacement :factory_bot
+      g.factory_bot dir: "spec/factories"
+    end
   end
 end