Explicitly name the directory from which the vault update must be done

[philippb90]

The section in the docs (https://docs.interlay.io/#/vault/guide?id=_2-re-download-the-binary-and-setup-script) does not explicitly say that you need to run the commands from the same dir that you used for installing.

I.e. the folder that contains the interlay-vault.service file that you downloaded during install.