add news bullet

Author: teunbrand

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* New `make_constructor()` function that builds a standard constructor for
+  Geom and Stat classes (@teunbrand, #6142).
 * In continuous scales, when `breaks` is a function and `n.breaks` is set, the 
   `n.breaks` will be passed to the `breaks` function. Previously, `n.breaks` 
   only applied to the default break calculation (@teunbrand, #5972)