instructions for building on a Chromebook

Just in case anyone wants to build the examples on the ChromeOS Linux environment, a number of libraries are not installed by default:

```sh
sudo apt install pkg-config libx11-dev libgl-dev libxcursor-dev libxi-dev libxrandr-dev libxxf86vm-dev libwayland-dev libasound2-dev libpulse-dev libxinerama-dev
```

After this, at least the `snake` example builds and runs just fine.