Update docs to ask users to provide the username for the service when using our CMS

[neurosnap]

I think we should suggest users provide their username for this service when SSH'ing into our CMS. This will allow two things:

• their local username doesn't leak into our logs
• we can allow the same public key to be used by multiple accounts

https://news.ycombinator.com/item?id=31178373

Really cool. But obviously this will leak ssh private keys and your username to lists.sh To prevent this I guess you have specify a username and create a specific key and use that: ssh -i key unknown@lists.sh

[neurosnap]

Just deployed this change, closing.