Design doc overstates which identifiers trigger automatic refresh

One of the design documents describing embedded/nested identity references states that three specific kinds of identifiers all trigger an automatic refresh when referenced. The core specification itself is narrower: only two of those three trigger it, and the third is explicitly listed among the identifiers that stay static and do not auto-update.

Pre-existing inaccuracy in the design document, not something the recent authentication work introduced or touched. Low priority — the feature area this affects isn't built yet — but worth a quick correction to keep the document honest whenever someone next touches it.

Locate the design document describing embedded or nested identity references and compare its automatic-refresh statement with the core specification. Correct the document so only the two specified identifier types trigger refresh, while the third is listed as static; done means the design document matches the specification.

Written by the indexing model from the issue text.