docs: added workflow hooks docs + changed workflow response (#8364)

* docs: added workflow hooks docs + changed workflow response

* Update page.mdx

www/apps/book/app/advanced-development/workflows/advanced-example/page.mdx

@@ -205,8 +205,11 @@ With the steps ready, you'll create the workflow that runs these steps to update
 
 Change the content of `src/workflows/update-product-erp/index.ts` to the following:
 
-```ts title="src/workflows/update-product-erp/index.ts" collapsibleLines="1-5" expandButtonLabel="Show Imports"
-import { createWorkflow } from "@medusajs/workflows-sdk"
+```ts title="src/workflows/update-product-erp/index.ts" collapsibleLines="1-8" expandButtonLabel="Show Imports"
+import { 
+  createWorkflow,
+  WorkflowResponse,
+} from "@medusajs/workflows-sdk"
 import { UpsertProductDTO } from "@medusajs/types"
 import updateProduct from "./steps/update-product"
 import updateErp from "./steps/update-erp"
@@ -219,10 +222,10 @@ const updateProductAndErpWorkflow = createWorkflow(
   const product = updateProduct(input)
   const erpData = updateErp(input)
 
-  return {
+  return new WorkflowResponse({
     product,
     erpData,
-  }
+  })
 })
 
 export default updateProductAndErpWorkflow