add news bullet

Author: teunbrand

NEWS.md

@@ -10,6 +10,8 @@
 * Patterns and gradients are now also enabled in `geom_sf()` 
   (@teunbrand, #5716).
 * `stat_bin()` deals with non-finite breaks better (@teunbrand, #5665).
+* `geom_tile()` computes default widths and heights per panel instead of
+  per layer (@teunbrand, #5740).
 
 # ggplot2 3.5.0