config: introduce an utf-8 character so that editors are forced to use utf-8

…and if they don’t, the user can fix the editor setup at least.

See also http://bugs.i3wm.org/864

i3status.conf

@@ -1,3 +1,11 @@
+# i3status configuration file.
+# see "man i3status" for documentation.
+
+# It is important that this file is edited as UTF-8.
+# The following line should contain a sharp s:
+# ß
+# If the above line is not correctly displayed, fix your editor first!
+
 general {
         colors = true
         interval = 5