documentation seems incorrect

This seems to be a contradiction:

```
import spi
spi = SPI("/dev/spidev1.0")
```

One would have to do either of the following:

```
from spi import *
spi = SPI("/dev/spidev1.0")
```

```
import spi
x = spi.SPI("/dev/spidev1.0")
```
