Add SPDX header

diff --git a/verilog/rtl/uprj_netlists.v b/verilog/rtl/uprj_netlists.v
index 450b220..3537de8 100644
--- a/verilog/rtl/uprj_netlists.v
+++ b/verilog/rtl/uprj_netlists.v

@@ -1,3 +1,17 @@
+// SPDX-FileCopyrightText: 2020 Efabless Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// SPDX-License-Identifier: Apache-2.0
 
 // Include caravel global defines for the number of the user project IO pads 
 `include "defines.v"