Add notice about size attribute

Author: Tom Doan

README.md

@@ -58,7 +58,7 @@ Name                | Type     | Default      | Description
 ------------------- | -------- | ------------ | -----------
 `classic`           | boolean  | false        | The default behavior is to move the selected item to the top. If you want the order of items to remain static, then set this to `true`.
 `customClass`       | string   | arrow        | The class name to customize the drop-down menu style. The default `arrow` class displays a chevron-type arrow icon. Two additional helper classes are built in (add either or both to `arrow`): `triangle` converts the chevron into a solid triangle; `small` renders the arrow icon at half size.
-`height`            | number   | 50           | The drop-down menu height. The minimum value is 8.
+`height`            | number   | 50           | The drop-down menu item height. The minimum value is 8. Note that the maximum number of items displayed when the menu is opened is determined by the `size` attribute of the `<select>` element.
 `hoverIntent`       | number   | 200          | The wait period (in milliseconds) before collapsing the drop-down menu after you hover off of it. If you hover back onto the menu within the wait period, it will remain open. The minimum value is 0.
 `selectedDelimiter` | string   | ;            | The separator character to use for the list of selected values in a multi-select menu.
 `selectedMarker`    | string   | **&#10003;** | The icon or symbol to mark that an item is selected. HTML is accepted (e.g., `<i class="fa fa-check"></i>`).