add that the base IRI is also a base for nested resources

jsonschema-core.md

@@ -913,8 +913,9 @@ fragment).
 When the value of this keyword is resolved against the current base IRI, the
 resulting absolute IRI then serves as the identifier for the schema resource and
 as a base IRI for relative IRI references in keywords within that schema
-resource, in accordance with [RFC 3987 section 6.5](#rfc3987) and
-[RFC 3986 section 5.1.1](#rfc3986) regarding base IRIs embedded in content.
+resource and for nested schema resources, in accordance with [RFC 3987 section
+6.5](#rfc3987) and [RFC 3986 section 5.1.1](#rfc3986) regarding base IRIs
+embedded in content.
 
 Note that this IRI is an identifier and not necessarily a network locator. In
 the case of a network-addressable URL, a schema need not be downloadable from