bpo-39050: The Help button in IDLE's config menu works again (GH-17611)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
diff --git a/Lib/idlelib/configdialog.py b/Lib/idlelib/configdialog.py
index aaf319b..0e007b5 100644
--- a/Lib/idlelib/configdialog.py
+++ b/Lib/idlelib/configdialog.py
@@ -210,7 +210,7 @@
         """
         page = self.note.tab(self.note.select(), option='text').strip()
         view_text(self, title='Help for IDLE preferences',
-                 text=help_common+help_pages.get(page, ''))
+                  contents=help_common+help_pages.get(page, ''))
 
     def deactivate_current_config(self):
         """Remove current key bindings.