Well the implication is that:

  - there are such docs
  - you can find them
  - they won't lie to you
  - they'll be enough to give you a picture of how everything works

It's great that Docker fits this criteria, but in general tools that let you cut out a few of those steps and inspect how the actual thing is running live are also nice.

Ideally, consider using both: trust the docs, but validate regardless to have more confidence.