Got rid of hardcoded max in settings

apps/daisy/settings.js

@@ -34,7 +34,7 @@
     '< Back': back,
     'Colour': {
       value: 0 | color_options.indexOf(s.color),
-      min: 0, max: 5,
+      min: 0, max: color_options.length - 1,
       format: v => color_options[v],
       onchange: v => {
         s.color = color_options[v];
@@ -66,7 +66,7 @@
     },
     'Ring Display': {
       value: 0 | ring_options.indexOf(s.ring),
-      min: 0, max: 5,
+      min: 0, max: ring_options.length - 1,
       format: v => ring_options[v],
       onchange: v => {
         s.ring = ring_options[v];