Package name in generated doc string seems odd

I have an interface for which I generate a mock using:

```
//go:generate go run github.com/gojuno/minimock/v3/cmd/minimock -g -s _mock.go -i ./api.MyClient -o ./internal/api/mocks/
```

It generates me the following code:

```
import (
"context"
"sync"
mm_atomic "sync/atomic"
mm_time "time"

"github.com/florianloch/some_service/api"
"github.com/gojuno/minimock/v3"
)

// MyClientMock implements mm_api.MyClient
type MyClientMock struct {
```

It of course does not affect compilation but it's irritating to get the package name prefixed with `mm_` in the doc string.

If that is something worth fixing I could take a look at it.