message: docs: document data attributes
diff: @@ -64,6 +64,7 @@ React.render(c, container);
  |----------|----------------|----------|--------------|
  |id | html id to set on the component wrapper | String | '' |
  |className | additional css class of root dom node | String | '' |
  +|data-\* | html data attributes to set on the component wrapper | String | '' |
  |prefixCls | prefix class | String | '' |
  |animation | dropdown animation name. only support slide-up now | String | '' |
  |transitionName | dropdown css animation name | String | '' |
  