Add info about access logs on stdout

[jakubdyszkiewicz]

TrafficLog can be used to log on stdout with path: /dev/stdout. Add this as a tip to docs

[xbauquet]

I think #222 should close this issue.
Let me know if you think we should give more informations about it.

[github-actions]

This issue was inactive for 30 days it will be reviewed in the next triage meeting and might be closed.
If you think this issue is still relevant please comment on it promptly or attend the next triage meeting.

[github-actions]

Automatically closing the issue due to having one of the "closed state label".