Updated readme

Author: vishnugt

README.md

@@ -398,10 +398,14 @@ Or using the index object:
 
 `index.addDocuments(documents: Document<T>[]): Promise<EnqueuedUpdate>`
 
+`index.addDocumentsInBatch(documents: Document<T>[], batchSize = 1000): Promise<EnqueuedUpdate[]>`
+
 - Add or update multiple documents:
 
 `index.updateDocuments(documents: Document<T>[]): Promise<EnqueuedUpdate>`
 
+`index.updateDocumentsInBatch(documents: Document<T>[], batchSize = 1000): Promise<EnqueuedUpdate[]>`
+
 - Get Documents:
 
 `index.getDocuments(params: getDocumentsParams): Promise<Document<T>[]>`