Docs: how to add a custom connector / fetcher

[ahmetvural79]

A connector turns a remote source (token + config) into the markdown-shaped export the core ingests. Document the contract so people can add their own.

Scope

• explain the export shape the core connector expects
• a minimal worked example (a tiny REST source to export)
• where config + token (vault) live
• link from README + docs/ARCHITECTURE.md