Added migrations for CreatingGroupCategories

• Added:
- migrations for CreatingGroupCategories

db/migrate/20200727224633_create_group_categories.rb

@@ -0,0 +1,8 @@
+class CreateGroupCategories < ActiveRecord::Migration[5.2]
+  def change
+    create_table :group_categories do |t|
+      t.timestamps
+      t.string :text, null: false, default: ''
+    end
+  end
+end