fix the logic what user nav buttom shows when a user login in admin.html.erb!
create controller admin::six_categories!
edit for admin::sixbook_categories and setup its routes!
edit for views/admin/sixbook_categories/index, edit, and _form and set for permitted_params!
create controller admin::locations!
edit for location routes and permitted_params!
edit for controller admin::location!
finish for locations views and model setting!
creat controller admin::artists!
edit for artist routes, siderbar, and permitted_params!
edit for controller admin::artists!!
finish for aritsts views!