add unity doc.

unity/PICO-Unity-Integration-SDK-release_3.4.0/Enterprise/Scripts/Model/Point3D.cs

@@ -0,0 +1,18 @@
+namespace Unity.XR.PICO.TOBSupport
+{
+    public class Point3D
+    {
+        public double x;
+        public double y;
+        public double z;
+
+        public Point3D()
+        {
+        }
+
+        public override string ToString()
+        {
+            return $"Point3D:{nameof(x)}: {x}, {nameof(y)}: {y}, {nameof(z)}: {z}";
+        }
+    }
+}