docs: added region-related documentation pages (#2845)

* docs: added region doc pages

* docs: small fixes

www/docs/sidebars.js

@@ -220,6 +220,11 @@ module.exports = {
           type: "category",
           label: "Storefront",
           items: [
+            {
+              type: "doc",
+              id: "advanced/storefront/use-regions",
+              label: "Use Regions"
+            },
             {
               type: "doc",
               id: "guides/carts-in-medusa",
@@ -256,6 +261,11 @@ module.exports = {
           type: "category",
           label: "Admin",
           items: [
+            {
+              type: "doc",
+              id: "advanced/admin/manage-regions",
+              label: "Manage Regions"
+            },
             {
               type: "doc",
               id: "advanced/admin/import-products",
@@ -417,6 +427,11 @@ module.exports = {
           id: "advanced/backend/batch-jobs/index",
           label: "Batch Jobs"
         },
+        {
+          type: "doc",
+          id: "advanced/backend/regions/overview",
+          label: "Regions"
+        },
         {
           type: "doc",
           id: "advanced/backend/taxes/inclusive-pricing",