remove header from BoomConfigs.scala
-//******************************************************************************
-// Copyright (c) 2015 - 2019, The Regents of the University of California (Regents).
-// All Rights Reserved. See LICENSE and LICENSE.SiFive for license details.
-//------------------------------------------------------------------------------
-// Author: Christopher Celio, Abraham Gonzalez, Ben Korpan, Jerry Zhao
-//------------------------------------------------------------------------------
-
package example
import chisel3._
