Documention for STFT wrong

```
    inverse : bool
        To activate the iSTFT module or not. By default, it is False to save GPU memory.
```

should be

```
    iSTFT : bool
        To activate the iSTFT module or not. By default, it is False to save GPU memory.
```

You might also consider adding:

```
     The iSTFT kernel is not trainable. If you want a trainable iSTFT, use the iSTFT module.
```

