Add CONTRIBUTING.md file


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

Change-Id: I5a2a2d5e72f2bfa0d0045dea34676f1b5daaaec0
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
commit49895403b0b8bf74825c6ae4fe332fdddfd68d92
parent9a1e3c6c61b4532bef18cbcab94ac0e564fedce2
authorKai Köhne <kai.koehne@qt.io>
committerKai Köhne <kai.koehne@qt.io>
commit timeTue, 21 Apr 2026 07:20:51 +0000