Add CONTRIBUTING.md file


Point potential contributors to contribute.qt-project.org.

Change-Id: I86658d792eba280191c9926ad2eff3072ceefbdc
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
commit6fcb81b8630721c5fcb7c0a8e58e1b08b37ef585
parent3c930cf77e2f31cf1964b566cdbaa38f4bc86360
authorKai Köhne <kai.koehne@qt.io>
committerKai Köhne <kai.koehne@qt.io>
commit timeTue, 21 Apr 2026 07:21:23 +0000