Update USERS.md

Add a few other engines that use meshoptimizer

Author: zeux

USERS.md

@@ -34,6 +34,9 @@ If you are shipping an engine that is using meshoptimizer, listing the library i
 - [The Forge](https://theforge.dev/)
 - [Godot](https://godotengine.org/)
 - [HypeHype](https://hypehype.com/en)
+- [Luxe Engine](https://luxeengine.com/)
+- [LWJGL](https://www.lwjgl.org/)
+- [Qt Quick 3D](https://doc.qt.io/qt-6/qtquick3d-index.html)
 - [Roblox](https://www.roblox.com/)
 - [Unigine](https://unigine.com/)
 - [Wicked Engine](https://wickedengine.net/)