Correct missing template error page

- Correct controller path "app/controller/books_controller.rb" to "app/controllers/books_controller.rb"
- Add space after "NOTE:"

Ref - https://github.com/rails/rails/pull/46342

actionpack/lib/action_dispatch/middleware/templates/rescues/missing_exact_template.html.erb

@@ -7,10 +7,10 @@
 
   <div class="summary">
     <p>
-      <strong>NOTE:</strong>Rails usually expects a controller action to render a view template with the same name. 
+      <strong>NOTE:</strong> Rails usually expects a controller action to render a view template with the same name.
     </p>
     <p>
-      For example, a <code>BooksController#index</code> action defined in <code>app/controller/books_controller.rb</code> should have a corresponding view template 
+      For example, a <code>BooksController#index</code> action defined in <code>app/controllers/books_controller.rb</code> should have a corresponding view template 
       in a file named <code>app/views/books/index.html.erb</code>.
     </p>
     <p>