Closes DOCS-66.
Adds a `[!NOTE]` callout to `docs/admin/monitoring/logs.md` documenting
that `--log-human=""` (empty string) does not disable human-readable
logging; the working value is `--log-human=/dev/null`.
## Context
Reported by Bjorn Robertsson in `#docs` on 2026-04-29. Operators trying
to silence the human-readable log stream had been setting `--log-human`
(or `CODER_LOGGING_HUMAN`) to an empty string and getting unchanged log
output. The empty-string path hits a 2023-vintage code path that falls
back to the default `/dev/stderr` instead of disabling output.
This PR documents the workaround on the admin-facing logs page. The CLI
flag reference under `docs/reference/cli/server.md` is auto-generated
and intentionally left unchanged. A separate engineering issue may be
worth filing to fix the root cause (empty string should either disable
or surface a warning).
> [!NOTE]
> This is a docs-only change. No product code was modified.
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*Generated by Coder Agents on behalf of @nickvigilante.*
Nick Vigilante