Log which server config is being used on startup

[Christoffer Åström]

What is the problem you want to solve?

Trying to upgrade to v0.18.0 and took a while until I realised it was using an older server config version since I had

keys:
  fs:
    path: /xyz

How do you want to solve it?

Maybe it could log what server config version is being used and not only

Error: no admin identity specified