tweak update message

- Since we need to show this to new users until AnkiDroid is updated,
use a wording that doesn't seem so out of place to new users.
- Avoid mentioning syncing, since the user may not sync, and the
modSchema() call will allow the user to confirm anyway.
- Let the user know they can change their mind about AnkiDroid by
visiting the preferences.

ftl/core/scheduling.ftl

@@ -93,7 +93,7 @@ scheduling-custom-study = custom study
 
 ## Scheduler upgrade
 
-scheduling-update-soon = You are currently using Anki's old scheduler, which will be retired soon. Please make sure all of your devices are in sync, and then update to the new scheduler.
+scheduling-update-soon = Anki 2.1 comes with a new scheduler, which fixes a number of issues that previous Anki versions had. Updating to it is recommended.
 scheduling-update-done = Scheduler updated successfully.
 scheduling-update-button = Update
 scheduling-update-later-button = Later

qt/aqt/deckbrowser.py

@@ -386,7 +386,10 @@ class DeckBrowser:
         self.mw.col.upgrade_to_v2_scheduler()
 
         # not translated, as 2.15 should not be too far off
-        if askUser("Do you sync with AnkiDroid 2.14 or earlier?", defaultno=True):
+        if askUser(
+            "Do you use AnkiDroid <= 2.14, or plan to use it in the near future? If unsure, choose No. You can adjust the setting later in the preferences screen.",
+            defaultno=True,
+        ):
             prefs = self.mw.col.get_preferences()
             prefs.sched.new_timezone = False
             self.mw.col.set_preferences(prefs)