タグ説明移行 (#422) (#423)

Reviewed-on: #423
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/models/tag_description.rb

@@ -0,0 +1,3 @@
+class TagDescription < ApplicationRecord
+  belongs_to :tag
+end

backend/app/models/tag_description_version.rb

@@ -0,0 +1,3 @@
+class TagDescriptionVersion < ApplicationRecord
+  ;
+end

backend/app/models/wiki_page.rb

@@ -48,8 +48,11 @@ class WikiPage < ApplicationRecord
     page
   end
 
-  def pred_revision_id(revision_id) =
-      wiki_revisions.where('id < ?', revision_id).order(id: :desc).limit(1).pick(:id)
-  def succ_revision_id(revision_id) =
-      wiki_revisions.where('id > ?', revision_id).order(id: :asc).limit(1).pick(:id)
+  def pred_revision_id revision_id
+    wiki_revisions.where('id < ?', revision_id).order(id: :desc).limit(1).pick(:id)
+  end
+
+  def succ_revision_id revision_id
+    wiki_revisions.where('id > ?', revision_id).order(id: :asc).limit(1).pick(:id)
+  end
 end