add javadoc for new common.metadata package

Signed-off-by: Varun Bansal <bansvaru@amazon.com>

Author: linuxpi

server/src/main/java/org/opensearch/common/metadata/package-info.java

@@ -0,0 +1,10 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+/** Common OpenSearch metadata constructs */
+package org.opensearch.common.metadata;