Minor: add copyright header

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchIndexScanRule.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 package org.opensearch.sql.opensearch.planner.physical;
 
 import org.apache.calcite.plan.RelOptTable;

opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchLimitIndexScanRule.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 package org.opensearch.sql.opensearch.planner.physical;
 
 import java.util.Objects;