Add `cei:index` to `cei:persName`
Created by: GVogeler
schema allows already cei:placeName/cei:index to encode terms like "castle", "church", "chapel" as part of place name. Does this fit to cei:persName too? TEI allows term in persName as well (http://www.tei-c.org/release/doc/tei-p5-doc/en/html/ref-term.html).