Update DartPad Privacy Notice (#6489)

This updates the privacy policy for DartPad to include AI features
(prompts) that may be sent to the backend.

Author: johnpryan

src/content/tools/dartpad/privacy.md

@@ -9,7 +9,8 @@ language and libraries. Source code entered into DartPad may be sent to servers
 running in Google Cloud to be analyzed for errors/warnings, compiled to
 JavaScript, and returned to the browser.
 
-Source code entered into DartPad may be stored, processed, and aggregated in
+Source code, or prompts used to generate source code
+entered into DartPad may be stored, processed, and aggregated in
 order to improve the user experience of DartPad and other Dart tools. For
 example, we may use the source code to help offer better code completion
 suggestions. The raw source code is deleted after no more than 60 days.