docs: revise main docs outline (#10502)

www/apps/book/app/learn/fundamentals/events-and-subscribers/data-payload/page.mdx

@@ -0,0 +1,69 @@
+import { TypeList } from "docs-ui"
+
+export const metadata = {
+  title: `${pageNumber} Event Data Payload`,
+}
+
+# {metadata.title}
+
+In this chapter, you'll learn how subscribers receive an event's data payload.
+
+## Access Event's Data Payload
+
+When events are emitted, they’re emitted with a data payload. 
+
+The object that the subscriber function receives as a parameter has an `event` property, which is an object holding the event payload in a `data` property with additional context.
+
+For example:
+
+export const highlights = [
+  ["7", "event", "The event details."],
+  ["8", "{ id: string }", "The type of expected data payloads."],
+]
+
+```ts title="src/subscribers/product-created.ts" highlights={highlights} collapsibleLines="1-5" expandButtonLabel="Show Imports"
+import type {
+  SubscriberArgs,
+  SubscriberConfig,
+} from "@medusajs/framework"
+
+export default async function productCreateHandler({
+  event,
+}: SubscriberArgs<{ id: string }>) {
+  const productId = event.data.id
+  console.log(`The product ${productId} was created`)
+}
+
+export const config: SubscriberConfig = {
+  event: "product.created",
+}
+```
+
+The `event` object has the following properties:
+
+<TypeList types={[
+  {
+    name: "data",
+    type: "`object`",
+    description: "The data payload of the event. Its properties are different for each event."
+  },
+  {
+    name: "name",
+    type: "string",
+    description: "The name of the triggered event."
+  },
+  {
+    name: "metadata",
+    type: "`object`",
+    description: "Additional data and context of the emitted event.",
+    optional: true
+  },
+]} sectionTitle="Access Event's Data Payload" />
+
+This logs the product ID received in the `product.created` event’s data payload to the console.
+
+{/* ---
+
+## List of Events with Data Payload
+
+Refer to [this reference](!resources!/events-reference) for a full list of events emitted by Medusa and their data payloads. */}