Add basic version of post show page

config/locales/en.yml

@@ -1,4 +1,6 @@
 en:
   errors:
+    unauthorized: 'You are not authorized'
     post:
-      create: 'Post create error: %{message}'
+      create: 'Post create error: %{message}'
+      update: 'Post update error: %{message}'

config/routes.rb

@@ -13,6 +13,6 @@ Rails.application.routes.draw do
   devise_for :users
 
   resources :boards, only: [:show]
-  resources :posts, only: [:index, :create]
+  resources :posts, only: [:index, :create, :show, :update]
   resources :post_statuses, only: [:index]
 end