This one occurrence wasn't updated:
$ git grep "nix-build nixos/release.nix -A manual"
nixos/doc/manual/README: nix-build nixos/release.nix -A manual.x86_64-linux
nixos/doc/manual/development/meta-attributes.xml:<screen><prompt>$ </prompt>nix-build nixos/release.nix -A manual</screen>
nixos/doc/manual/development/writing-documentation.xml:<screen>nix-build nixos/release.nix -A manual.x86_64-linux</screen>