add subtext to changelog

Author: raphael-theriault-swi

.chloggen/node-import.yaml

@@ -13,4 +13,6 @@ issues: [3414]
 # (Optional) One or more lines of additional information to render under the primary note.
 # These lines will be padded with 2 spaces and then inserted directly into the document.
 # Use pipe (|) for multiline entries.
-subtext:
+subtext: |
+  The new UseImport configuration overrides the default injected --require flag with an --import flag that supports ESM.
+  Requires Node.js 18 or later.