feat(overload): add readme instruction

apps/overload/src/app/vehicle.utils.ts

@@ -0,0 +1,55 @@
+type VehicleType = 'bus' | 'car' | 'moto' | 'bicycle' | 'boat';
+type Fuel = 'diesel' | 'petrol' | 'electric';
+
+interface Bicycle {
+  type: 'bicycle';
+}
+
+interface Car {
+  fuel: Fuel;
+  type: 'car';
+}
+
+interface Moto {
+  fuel: Fuel;
+  type: 'moto';
+}
+
+interface Bus {
+  capacity: number;
+  isPublicTransport: boolean;
+  type: 'bus';
+}
+
+interface Boat {
+  capacity: number;
+  type: 'boat';
+}
+
+type Vehicle = Bicycle | Car | Moto | Bus | Boat;
+
+export function createVehicle(
+  type: VehicleType,
+  fuel?: Fuel,
+  capacity?: number,
+  isPublicTransport?: boolean
+): Vehicle {
+  switch (type) {
+    case 'bicycle':
+      return { type };
+    case 'car':
+    case 'moto':
+      if (!fuel) throw new Error(`fuel property is missing for type ${type}`);
+      return { fuel, type };
+    case 'boat':
+      if (!capacity)
+        throw new Error(`capacity property is missing for type boat`);
+      return { capacity, type };
+    case 'bus':
+      if (!capacity)
+        throw new Error(`capacity property is missing for type bus`);
+      if (!isPublicTransport)
+        throw new Error(`isPublicTransport property is missing for type bus`);
+      return { capacity, isPublicTransport, type };
+  }
+}