Update class-based DTO notes in reference docs.

Closes #2558.
Related: #2635.

src/main/asciidoc/repository-projections-dto-limitations.adoc

@@ -1 +1 @@
-NOTE: Class based projections do not work with native queries. As a workaround you may use named queries with `ResultSetMapping` or the Hibernate specific https://docs.jboss.org/hibernate/orm/6.0/javadocs/org/hibernate/transform/ResultTransformer.html[`ResultTransformer`]
+NOTE: Class-based projections with JPQL is limited to *constructor expressions* in your JPQL expression, e.g. `SELECT new com.example.NamesOnly(u.firstname, u.lastname) from User u`. (Note the usage of a FQDN for the DTO type!) This JPQL expression can be used in `@Query` annotations as well where you define any named queries. And it's important to point out that class-based projections do not work with native queries AT ALL. As a workaround you may use named queries with `ResultSetMapping` or the Hibernate specific https://docs.jboss.org/hibernate/orm/6.0/javadocs/org/hibernate/transform/ResultTransformer.html[`ResultTransformer`]