Add admin panel and make it work for user resource

app/models/user.rb

@@ -1,4 +1,8 @@
 class User < ApplicationRecord
+  devise :database_authenticatable, :registerable,
+         :recoverable, :rememberable, :validatable,
+         :confirmable
+
   enum role: [:user, :moderator, :admin]
   after_initialize :set_default_role, if: :new_record?
 
@@ -12,8 +16,4 @@ class User < ApplicationRecord
     gravatar_id = Digest::MD5::hexdigest(email.downcase)
     "https://secure.gravatar.com/avatar/#{gravatar_id}"
   end
-
-  devise :database_authenticatable, :registerable,
-         :recoverable, :rememberable, :validatable,
-         :confirmable
 end