Update README.md

fix bundler gateway

Author: zyjblockchain

README.md

@@ -320,7 +320,7 @@ bundle, err := utils.NewBundle(items...)
 ```
 
 #### Send Item to Bundler
-It is not necessary, The purpose is to create an index for the Bundler gateway
+Bundler network provides guaranteed data seeding and instant data accessibility
 ```go
 resp, err := w.Client.BatchSendItemToBundler(items)
 ```
@@ -341,4 +341,4 @@ for _, item := range bundle.Items {
   assert.NoError(t, err)
 }
 ```
----
+---