docs(influxdb3): confirm whether to document --rbac-authoring-disabled

`content/shared/influxdb3-cli/config-options.md` has an empty environment
variable cell for `rbac-authoring-disabled`. The flag gates custom role
authoring, which isn't shipped yet — env var and default are confirmed
(`INFLUXDB3_RBAC_AUTHORING_DISABLED`, default `true`), but whether/when to
document it is a product-timing question.

Tracked in DAR: influxdata/DAR#743

Blocked until that's answered.

Read content/shared/influxdb3-cli/config-options.md to inspect the empty environment-variable cell, then review the linked DAR issue, influxdata/DAR#743, for the product-timing decision. The work is done when that decision establishes whether and when the rbac-authoring-disabled option should be documented and the cell is updated accordingly.

Written by the indexing model from the issue text.