docs: contentful part 2 (#484)

* Create making-your-store-more-powerful-with-contentful.md

* Update sidebars.js

www/docs/sidebars.js

@@ -69,6 +69,10 @@ module.exports = {
               type: "doc",
               id: "how-to/headless-ecommerce-store-with-gatsby-contentful-medusa",
             },
+            {
+              type: "doc",
+              id: "how-to/making-your-store-more-powerful-with-contentful",
+            },
           ],
         },
         {