docs: a website session is a secret without a reference - configuration-tiers says why raw login writes it into the secrets file itself and that the 1Password safeguards do not cover it; the secret tier row names it (#169 close)

Files changed:
- docs/explanation/configuration-tiers.md
- docs/reference/configuration.md

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

docs/reference/configuration.md

@@ -76,7 +76,7 @@ declares the tier it belongs to:
 |------|------|-------|
 | `instance` | `wikitool.json`, committed | What belongs to the corpus and is the same in every clone |
 | `checkout` | `.wikitool-local.json`, gitignored | What is true only for this clone on this machine |
-| `secret` | neither | Tokens and passwords - both files hold only a reference |
+| `secret` | neither | Tokens, passwords and website sessions - both files hold only a reference, and a session from `raw login` none ([below](#fetch-routes)) |
 
 Each file is a JSON object of sections, one per feature, beside two keys of its own: