doc: add missing copyright headers

src/test/caches_tests.cpp

@@ -1,3 +1,7 @@
+// Copyright (c) The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://opensource.org/license/mit.
+
 #include <node/caches.h>
 #include <util/byte_units.h>
 

src/test/kernel/block_data.h

@@ -1,3 +1,7 @@
+// Copyright (c) The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://opensource.org/license/mit.
+
 #ifndef BITCOIN_TEST_KERNEL_BLOCK_DATA_H
 #define BITCOIN_TEST_KERNEL_BLOCK_DATA_H
 #include <array>