Update classes option to reflect the actual values (#10)

Author: Guirec

options.md

@@ -281,18 +281,26 @@ Collection of internally used HTML classes. Default values:
 
 ```
 {
+  swipeable: 'glide--swipeable',
+  dragging: 'glide--dragging',
   direction: {
     ltr: 'glide--ltr',
     rtl: 'glide--rtl'
   },
-  slider: 'glide--slider',
-  carousel: 'glide--carousel',
-  swipeable: 'glide--swipeable',
-  dragging: 'glide--dragging',
-  cloneSlide: 'glide__slide--clone',
-  activeNav: 'glide__bullet--active',
-  activeSlide: 'glide__slide--active',
-  disabledArrow: 'glide__arrow--disabled'
+  type: {
+    slider: 'glide--slider',
+    carousel: 'glide--carousel'
+  },
+  slide: {
+    clone: 'glide__slide--clone',
+    active: 'glide__slide--active'
+  },
+  arrow: {
+    disabled: 'glide__arrow--disabled'
+  },
+  nav: {
+    active: 'glide__bullet--active'
+  }
 }
 ```