Update mesh.js

#6193 update code example to fix uv and include setting normals

src/scene/mesh.js

@@ -124,16 +124,17 @@ class GeometryVertexStream {
  *     0, 1, 0  // pos 3
  * ]);
  * const uvs = new Float32Array([
- *     0, 0, // uv 0
- *     1, 0, // uv 1
- *     1, 1, // uv 2
  *     0, 1  // uv 3
+ *     1, 1, // uv 2
+ *     1, 0, // uv 1
+ *     0, 0, // uv 0
  * ]);
  * const indices = [
  *     0, 1, 2, // triangle 0
  *     0, 2, 3  // triangle 1
  * ];
  * mesh.setPositions(positions);
+ * mesh.setNormals(pc.calculateNormals(positions, indices));
  * mesh.setUvs(0, uvs);
  * mesh.setIndices(indices);
  * mesh.update();