update news

Author: cpsievert

NEWS.md

@@ -27,6 +27,7 @@
 * An articial marker no longer appears when clearing a crosstalk selection of a plot with a colorbar (#1406).
 * Clearing a highlight event via crosstalk no longer deletes all the traces added since initial draw (#1436).
 * Recursive attribute validation is now only performed on recursive objects (#1315).
+* The `text` attribute is no longer collapsed to a string when `hoveron='fills+points'` (#1448). 
 
 # 4.8.0