docs: customer tiers tutorial (#14122)

* docs: customer tiers tutorial

* fix lint error

www/apps/resources/sidebars/how-to-tutorials.mjs

@@ -120,6 +120,13 @@ While tutorials show you a specific use case, they also help you understand how
         description:
           "Learn how to use prices from external systems for products.",
       },
+      {
+        type: "link",
+        title: "Customer Tiers",
+        path: "/how-to-tutorials/tutorials/customer-tiers",
+        description:
+          "Learn how to implement customer tiers in your Medusa store.",
+      },
       {
         type: "link",
         title: "First-Purchase Discounts",