Update README for Multi-Story Building Generation

README.md

@@ -121,7 +121,32 @@ foreach (var plan in plans)
 }
 ```
 
-### 5. Serialization
+### 5. Multi-Story Building Generation
+
+You can generate multi-story buildings by stacking compatible floor plans using `BuildingGenerator`.
+
+```csharp
+using ResPlan.Library;
+
+// 1. Load a pool of plans (load enough to find good matches)
+var plans = await PlanLoader.LoadPlansAsync(maxItems: 50, logger: logger);
+
+// 2. Generate a building
+var generator = new BuildingGenerator();
+// Attempt to stack 3 floors using the available plans
+Building building = generator.GenerateBuilding(plans, targetFloors: 3);
+
+Console.WriteLine($"Generated building with {building.Floors.Count} floors.");
+
+// 3. Render each floor (including generated stairs)
+foreach (var floor in building.Floors)
+{
+    // RenderFloor visualizes the plan plus additional geometries (e.g., stairs)
+    PlanRenderer.RenderFloor(floor, $"building_floor_{floor.FloorNumber}.png");
+}
+```
+
+### 6. Serialization
 
 To support binary serialization and handle special floating-point values (like `NaN` or `Infinity`) which are not standard in JSON, the library provides a helper class `PlanSerializer` using **MessagePack**.