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/fulfillment/module-options/page.mdx

@@ -38,14 +38,14 @@ module.exports = defineConfig({
               config: {
                 manual: {
                   // provider options...
-                }
-              }
-            }
+                },
+              },
+            },
           },
         ],
       },
     },
-  }
+  },
 })
 ```