Document every exported symbol and how callers use the library.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/bind-tsig-configuration.md

@@ -144,6 +144,6 @@ Ensure `db.example.com` exists with a valid SOA and NS records before loading th
 
 ## Related documentation
 
+- [Guide](guide.md) — how callers use AXFR, UPDATE, and TSIG
+- [API](api.md) — exported symbols
 - [Project specification](project-specification.md) — library scope, TSIG model, AXFR-only transfers
-- [Change 00001 spec](changes/00001-setup-project/spec.md) — full DNS operation catalog and BIND guide requirements
-- [Product backlog](backlog.md) — future work (e.g. IXFR)