Add OpenHFT in Spark plugin LICENSE (#1980)

Author: jbonofre

plugins/spark/v3.5/spark/LICENSE

@@ -573,3 +573,11 @@ Project URL: https://commons.apache.org/proper/commons-lang/
 License: Apache License 2.0 - https://www.apache.org/licenses/LICENSE-2.0.txt
 
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+
+This binary artifact contains OpenHFT.
+
+Copyright: 2014 Higher Frequency Trading http://www.higherfrequencytrading.com
+Project URL: https://github.com/OpenHFT
+License: Apache License 2.0 - https://www.apache.org/licenses/LICENSE-2.0.txt
+
+--------------------------------------------------------------------------------