[Bug Report] Chapter 8 Duplicate MaterialData Description

The book portion of Chapter 8 lists MaterialData as what is below, after describing an update for ModelData

```
package org.vulkanb.eng.model;

import java.util.List;

public record ModelData(String id, List<MeshData> meshes, String vtxPath, String idxPath) {
}
```

When it should be listed as blank since MaterialData is described earlier in the chapter.