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/resources/app/commerce-modules/auth/authentication-route/page.mdx

@@ -32,6 +32,6 @@ There are two ways the returned authentication token is useful:
 
 <Note title="Example">
 
-[How to register Customers using the authentication route](../../customer/register-customer-email/page.mdx).
+[How to register Customers using the authentication route](../../../storefront-development/customers/register/page.mdx).
 
 </Note>