GDBusConnection: note that exit-on-close is sometimes TRUE

GDBusConnection: note that exit-on-close is sometimes TRUE

g_bus_get_finish() and g_bus_get_sync() both document that the returned
object will usually have exit-on-close set to TRUE, but the property's
documentation specified that its default is FALSE. While that's
technically true from a GObject perspective, it's not accurate from the
API user's perspective.

https://bugzilla.gnome.org/show_bug.cgi?id=668163

Reviewed-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: David Zeuthen <zeuthen@gmail.com>