fine-tune NEWS

Author: MichaelChirico

NEWS.md

@@ -10,7 +10,7 @@
 
 1. Tests run again when some Suggests packages are missing, [#6411](https://github.com/Rdatatable/data.table/issues/6411). Thanks @aadler for the note and @MichaelChirico for the fix.
 
-2. All direct use of `NAMED` and some direct use of `LEVELS` has been removed from the package, reducing the use of non-API functions, see [#6420](https://github.com/Rdatatable/data.table/pull/6420) by Ivan Krylov. The work is on the overall issue [#6180](https://github.com/Rdatatable/data.table/issues/6180) reported by Michael Chirico.
+2. Continued work to remove non-API C functions, [#6180](https://github.com/Rdatatable/data.table/issues/6180). Thanks Ivan Krylov for the PR and for writing a clear and concise guide about the R API: https://aitap.codeberg.page/R-api/.
 
 # data.table [v1.16.0](https://github.com/Rdatatable/data.table/milestone/30)  (25 August 2024)