Update README.md (#1060)

Turns out Babylon.js uses Manifold too!

README.md

@@ -19,7 +19,7 @@ Here is an incomplete list of our users, whose integrations may be anywhere from
 | [Nomad Sculpt](https://apps.apple.com/us/app/id1519508653?mt=8&platform=ipad) | [Grid.Space](https://grid.space/) | [badcad](https://github.com/wrongbad/badcad) |
 | [Godot Engine](https://godotengine.org/) | [OCADml](https://github.com/OCADml/OManifold) | [Flitter](https://flitter.readthedocs.io/en/latest/) |
 | [BRL-CAD](https://brlcad.org/) | [PolygonJS](https://polygonjs.com/) | [Spherene](https://spherene.ch/) |
-| [trimesh](https://trimesh.org/) | [Gypsum](https://github.com/playkostudios/gypsum) | |
+| [Babylon.js](https://doc.babylonjs.com/features/featuresDeepDive/mesh/mergeMeshes#merging-meshes-with-constructive-solid-geometry) | [trimesh](https://trimesh.org/) | [Gypsum](https://github.com/playkostudios/gypsum) |
 
 ### Bindings & Packages