New comment by xtraeme on void-packages repository

https://github.com/void-linux/void-packages/pull/18049#issuecomment-570888538

Comment:
The correct way to update your system with xbps (unattended) is (as of 0.57.1_7):

```
# xbps-install -Syu xbps
# xbps-install -yu
```