add validations
update boards#create
update boards#index
update boards/index.html.erb
get 'boards/:id' => 'boards#show'
link_to boards#show
define boards#show
add boards/show.html.erb
add boards#edit
add boards#update
link_to boards#edit
link_to boards#destroy
add boards#destroy
resources :boards
update view url
update controller url
using form_for at boards#index
raise at boards#create
update BoardsController#params_board
update boards#edit