An option declared internal = true or visible = false is not shown to an
operator, so adding or changing one needs no documentation. A nix
option's own description renders into the generated options reference,
so for a change to that option's default, type or meaning an updated
description is its documentation, alongside docs/ and crate READMEs.
A change in what a service does for operators across hosts (what it
scrapes, serves or publishes) still needs a docs/ page or README, so a
description edit does not excuse it.