review classifier: docs-updated counts option descriptions, skips internal options

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.

.hyperhive/review-classifier.yml

@@ -45,7 +45,13 @@ classifications:
     description: >-
       A change to what an operator or user sees, such as a command, flag,
       option, endpoint, service or default, updates the matching page under
-      docs/ or the crate's README in the same diff.
+      docs/ or the crate's README in the same diff. For a nix option whose
+      own default, type or meaning changes, an updated `description` on that
+      option counts as the documentation. It does not cover a change in what
+      a service does for operators across hosts, such as what it scrapes,
+      serves or publishes: that needs a docs/ page or README. A nix option
+      declared `internal = true` or `visible = false` is not something an
+      operator sees, so adding or changing one needs none of these.
     polarity: positive
     threshold: 65
   - name: one-purpose