v0.2.1 — doctor advice named the old CLI binary

Corrects the advice oauth:doctor prints, and one comment in the shipped configuration.

Both told the reader to run vendor/bin/nix — nix db:migrate up for a missing table, and nix oauth:doctor in the note explaining how to generate a token encryption key. The rename to NAF replaced that binary with vendor/bin/naf. No behaviour changes; the commands themselves were never affected.