update changelog (imported from #1360)

Author: gregsdennis

jsonschema-core.md

@@ -3301,7 +3301,7 @@ to the document.
 
 ### draft-bhutton-json-schema-next
 - `contains` now applies to objects as well as arrays
-- Use IRIs instead of URIs
+- Use IRIs instead of URIs, including allowing unicode in plain-name fragments
 - Clarify that detecting duplicate IRIs for different schemas SHOULD raise an error
 - Consolidate and clarify the syntax and rationale for plain-name fragments
 - "$id" MUST be an absolute-IRI, without any fragment, even an empty one