[welcome] Update welcome example

- donate **does** have a corresponding branding setting
- show that "false" is a valid setting

src/modules/welcome/welcome.conf

@@ -14,15 +14,8 @@
 # which will hide the button.
 showSupportUrl:         true
 showKnownIssuesUrl:     true
-showReleaseNotesUrl:    true
-
-# If this Url is set to something non-empty, a "donate"
-# button is added to the welcome page alongside the
-# others (see settings, above). Clicking the button opens
-# the corresponding link. (This button has no corresponding
-# branding.desc string)
-#
-# showDonateUrl:  https://kde.org/community/donations/
+showReleaseNotesUrl:    false
+showDonateUrl:          https://kde.org/community/donations/
 
 # Requirements checking. These are general, generic, things
 # that are checked. They may not match with the actual requirements