Document how to add multiple items via batch request (https://github.com/woocommerce/woocommerce-blocks/pull/8266)

* Document how to add multiple items via batch request

* Remove “Add Items” section title

* Remove “data” part from JSON example payload

plugins/woocommerce-blocks/src/StoreApi/docs/cart.md

@@ -14,11 +14,6 @@
 -   [Update Customer](#update-customer)
 -   [Select Shipping Rate](#select-shipping-rate)
 
-Test:
-
--   Hello
--   Hello 2
-
 The cart API returns the current state of the cart for the current session or logged in user.
 
 All POST endpoints require [Nonce Tokens](nonce-tokens.md) and return the updated state of the full cart once complete.
@@ -339,6 +334,45 @@ Returns the full [Cart Response](#cart-response) on success, or an [Error Respon
 
 If you want to add supplemental cart item data before it is passed into `CartController::add_to_cart` use the [`woocommerce_store_api_add_to_cart_data`](https://github.com/woocommerce/woocommerce-blocks/blob/4d1c295a2bace9a4f6397cfd5469db31083d477a/docs/third-party-developers/extensibility/hooks/filters.md#woocommerce_store_api_add_to_cart_data) filter.
 
+If you want to add multiple items at once, you need to use the batch endpoint:
+
+```http
+POST /wc/store/v1/batch
+```
+
+The JSON payload for adding multiple items to the cart would look like this:
+
+```json
+{
+	"requests": [
+		{
+			"path": "/wc/store/v1/cart/add-item",
+			"method": "POST",
+			"cache": "no-store",
+			"body": {
+				"id": 26,
+				"quantity": 1
+			},
+			"headers": {
+				"Nonce": "1db1d13784"
+			}
+		},
+		{
+			"path": "/wc/store/v1/cart/add-item",
+			"method": "POST",
+			"cache": "no-store",
+			"body": {
+				"id": 27,
+				"quantity": 1
+			},
+			"headers": {
+				"Nonce": "1db1d13784"
+			}
+		}
+	]
+}
+```
+
 ## Remove Item
 
 Remove an item from the cart and return the full cart response, or an error.