Litecoin: Fix checkblock bench test

src/bench/checkblock.cpp

@@ -17,6 +17,9 @@ namespace block_bench {
 // a block off the wire, but before we can relay the block on to peers using
 // compact block relay.
 
+// Litecoin uses block height 878439, hash 0babe680f55a55d54339511226755f0837261da89a4e78eba4d6436a63026df8
+// which contains 3808 transactions.
+
 static void DeserializeBlockTest(benchmark::State& state)
 {
     CDataStream stream((const char*)block_bench::block413567,