message: add the description when probeType = 0
diff: @@ -120,7 +120,7 @@ The code results in a clickable vertical scrolling effect. better-scroll support
  - Type: `Number`
  - Default: `0`
  - Optional Value: `1`, `2`, `3`
  - - Usage: Sometimes we want to know the scrolling position. This setting regulates the probe aggressiveness or the frequency at which the `scroll` event is fired. Valid values are: `1`, `2`, `3`. When setted to 1, The scroll event is non-real time fired (after the screen scrolled for some time); When setted to 2, the scroll event is real-time fired during the screen scrolling; When setted to 3, the scroll event is real-time fired during not only the screen scrolling but also the momentum and bounce animation.
  + - Usage: Sometimes we want to know the scrolling position. This setting regulates the probe aggressiveness or the frequency at which the `scroll` event is fired. Valid values are: `1`, `2`, `3`. When setted to 1, The scroll event is non-real time fired (after the screen scrolled for some time); When setted to 2, the scroll event is real-time fired during the screen scrolling; When setted to 3, the scroll event is real-time fired during not only the screen scrolling but also the momentum and bounce animation. If not setted, the default value `0` means there is no scroll event is fired.
  ## preventDefault
  - Type: `Boolean`
  