Merge branch 'master' into docs/development

www/docs/sidebars.js

@@ -192,19 +192,10 @@ module.exports = {
                 },
               ]
             },
-            {
-              type: "doc",
-              id: "tutorial/adding-custom-functionality",
-              label: "Add Custom Functionality"
-            },
             {
               type: "doc",
               id: "how-to/notification-api",
             },
-            {
-              type: "doc",
-              id: "guides/fulfillment-api",
-            },
             {
               type: "doc",
               id: "guides/plugins",
@@ -213,6 +204,23 @@ module.exports = {
               type: "doc",
               id: "guides/carts-in-medusa",
             },
+            {
+              type: "doc",
+              id: "advanced/backend/migrations",
+              label: "Migrations"
+            },
+            {
+              type: "category",
+              label: 'Upgrade Guides',
+              collapsed: true,
+              items: [
+                {
+                  type: "doc",
+                  id: "advanced/backend/upgrade-guides/1-3-1",
+                  label: "v1.3.1"
+                },
+              ]
+            },
           ]
         }
       ]