add back license

Author: TheovanKraay

src/main/java/com/azure/cosmos/examples/bulk/sync/BulkWriter.java

@@ -1,4 +1,10 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
 
+/*
+  The BulkWriter class is an attempt to provide guidance for creating
+  a higher level abstraction over the existing low level Java Bulk API
+ */
 package com.azure.cosmos.examples.bulk.sync;
 
 import com.azure.cosmos.CosmosContainer;