[HDL] Add disclaimer for the frac_lut4_arith HDL codes
// - mode_bit[0] switch between arithmetic mode and LUT mode
// - mode_bit[1] switch between regular LUT mode and fracturable
// mode
+// Note : The HDL is a technology mapped netlist based on the Skywater
+// 130nm High-Density cell library.
+// TODO: Create a behavioral HDL version so that we are portable
+// between PDKs
// Coder : Xifan TANG
//-----------------------------------------------------
module frac_lut4_arith (
