Add copyright info

tobiasdiez · web-flow · commit 9713f9617efe · 2025-05-31T19:03:15.000+08:00
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -1,3 +1,9 @@
+<!--
+SPDX-FileCopyrightText: 2021 The meson-python developers
+
+SPDX-License-Identifier: MIT
+-->
+
 # Contributing
 
 Thank you for your interest in contributing to `meson-python`!
