add pages#index route
add pages#index action
create pages#index view
implement pages#index view
implement pages#index controller
add h1 to pages#new view
add main HTML tag and links CSS
add pages#edit route
add pages#edit action
create pages#edit view
implement pages#edit view
implement pages#edit action
refactor pages#new and pages#edit views
refactor pages#new and pages#edit actions (private method)
refactor pages#new and pages#edit actions (before action)
add pages#update routes