Mention that Winget can be used to install on Windows

**Description:**
The option to use Winget as a package manager to install CopyQ on Windows should be mentioned in the [Wiki](https://copyq.readthedocs.io/en/latest/) and the [website](https://hluk.github.io/CopyQ/).

**Solution:**
Alongside Chocolatey, add instructions to install using Winget to the [Wiki](https://copyq.readthedocs.io/en/latest/) and the [website](https://hluk.github.io/CopyQ/):
```winget install --id hluk.CopyQ```

P.S. This doesn't really classify as either a bug or a feature request, and I'm not even sure if this is the right repo for it.