add note about using u16 instead of u32

src/asset.h

@@ -36,7 +36,7 @@ struct mesh
 	glm::vec3* normals;
 	glm::vec2* uvs;
 	glm::vec3* colors;
-	u16* indices;
+	u16* indices; // NOTE: u16 to match tinygltf library output
 	glm::mat4* xform;
 };