Add route for roadmap and its tests

spec/routing/static_pages_routing_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+RSpec.describe 'static pages routing', :aggregate_failures, type: :routing do
+  it 'routes roadmap' do
+    expect(get: '/').to route_to(
+      controller: 'static_pages', action: 'roadmap'
+    )
+    
+    expect(get: '/roadmap').to route_to(
+      controller: 'static_pages', action: 'roadmap'
+    )
+  end
+end