docs: added customer storefront guides (#7685)

* added customer guides

* fixes to sidebar

* remove old customer registration guide

* fix build error

* generate files

* run linter

www/apps/book/app/advanced-development/admin/widgets/page.mdx

@@ -80,7 +80,7 @@ import { defineWidgetConfig } from "@medusajs/admin-shared"
 import { DetailWidgetProps, AdminProduct } from "@medusajs/types"
 
 const ProductWidget = ({ 
-  data
+  data,
 }: DetailWidgetProps<AdminProduct>) => {
   return (
     <div>