Documentation: Please specify owner/mode for the plugin auth identity files

[bruddy-lively]

In the documentation to setup the Slack plugin (possibly others as well), it's not mentioned what the owner/mode should be for the auth.key, auth.crt, auth.cas files when copied to /var/lib/teleport/plugins/slack/

I'm getting permission denied when running the teleport-slack start command. One can eventually modify the files to get them to work, but it would be faster and less effort if this was specified in the documentation.

https://goteleport.com/docs/enterprise/workflow/ssh-approval-slack/?scope=enterprise