docs(products): get clients shopping cart

Signed-off-by: Aleksandr_Zavadkin <[email protected]>

source/includes/_products.md.erb

@@ -486,7 +486,24 @@ curl 'https://<%= config[:api_endpoint] %>/products/cart?did=DEVICE_ID&shop_id=S
 ```
 
 ```jsx
-// Not implemented yet.
+ cart() {
+    return new Promise((resolve, reject) => {
+      this.push((() => {
+        try {
+          request('products/cart', {
+            params: {
+              shop_id: this.shop_id,
+            },
+          }).then( res => {
+            resolve(res)
+          });
+        } catch (error) {
+          reject(error)
+        }
+      }));
+    })
+  }
+
 ```
 
 ### HTTP Request