Second doc-directory of hyperhive#4042's Passive pass (see #4098 for
the first batch's full read-every-hit reasoning). Only one hit in this
whole directory: "Every page is generated at build time
(nix/packages/reference-docs.nix, hyperhive#3051)" -- a genuine catch,
same shape as #4098's swarm-SSO rewrites -- the actor is already named
parenthetically in the same sentence, so naming it as the grammatical
subject too is strictly clearer: "nix/packages/reference-docs.nix
(hyperhive#3051) generates every page at build time".
Verified: vale docs/crates/README.md before/after -- 1 -> 0 warnings.
The generated landing page's own H1 already said "Crate reference" —
the directory name should match. Rename docs/components/ -> docs/crates/
and update the generating derivation (nix/packages/reference-docs.nix),
its default.nix caller comment, and docs/README.md's link.
Fixes#3193
