Updated tutorial for Blackholio/pull/19 (#163)

Updated tutorial for clockworklabs/Blackholio#19

Co-authored-by: rekhoff <[email protected]>

Author: cloutiertyler

docs/unity/part-2.md

@@ -215,7 +215,7 @@ public partial struct Circle
     public uint player_id;
     public DbVector2 direction;
     public float speed;
-    public ulong last_split_time;
+    public SpacetimeDB.Timestamp last_split_time;
 }
 
 [Table(Name = "food", Public = true)]

docs/unity/part-3.md

@@ -485,7 +485,7 @@ public static Entity SpawnPlayerInitialCircle(ReducerContext ctx, uint player_id
     );
 }
 
-public static Entity SpawnCircleAt(ReducerContext ctx, uint player_id, uint mass, DbVector2 position, DateTimeOffset timestamp)
+public static Entity SpawnCircleAt(ReducerContext ctx, uint player_id, uint mass, DbVector2 position, SpacetimeDB.Timestamp timestamp)
 {
     var entity = ctx.Db.entity.Insert(new Entity
     {
@@ -499,7 +499,7 @@ public static Entity SpawnCircleAt(ReducerContext ctx, uint player_id, uint mass
         player_id = player_id,
         direction = new DbVector2(0, 1),
         speed = 0f,
-        last_split_time = (ulong)timestamp.ToUnixTimeMilliseconds(),
+        last_split_time = timestamp,
     });
     return entity;
 }