When manually creating the project and adding shader files FXC acts up

Looks like when you add hlsl files manually to a project via Add New File it creates `` elements in the project file, which can cause a problem, as in vs tries to compile the files itself using `fxc.exe`.

```
1>an error occurred while setting the initial search directory.
1>searches will be relative to the application's starting directory.
1>compilation failed; no code produced
```

We should adjust the wording in the early chapters somewhere, that this can happen and a workaround is to manually remove `` elements from the project file.