new revision migrations

db/migrate/20190917135359_create_status_revisions.rb

@@ -0,0 +1,9 @@
+class CreateStatusRevisions < ActiveRecord::Migration[5.2]
+  def change
+    create_table :status_revisions do |t|
+      t.bigint :status_id
+      t.string :text
+      t.timestamps
+    end
+  end
+end

db/migrate/20190917141707_add_revised_at_to_statuses.rb

@@ -0,0 +1,5 @@
+class AddRevisedAtToStatuses < ActiveRecord::Migration[5.2]
+  def change
+    add_column :statuses, :revised_at, :datetime
+  end
+end