message: docs(Tab): add offset-top rem unit desc
diff: @@ -205,7 +205,7 @@ In scrollspy mode, the list of content will be tiled
  | swipeable | Whether to switch tabs with swipe gestrue in the content | _boolean_ | `false` |
  | lazy-render | Whether to enable tab content lazy render | _boolean_ | `true` |
  | scrollspy `v2.3.0` | Whether to use scrollspy mode | _boolean_ | `false` |
  -| offset-top | Offset top when use sticky mode | _number \| string_ | `0` |
  +| offset-top `v2.8.7` | Sticky offset top , supports `px` ans `rem` unit, default `px` | _number \| string_ | `0` |
  | swipe-threshold | Set swipe tabs threshold | _number \| string_ | `4` | - |
  | title-active-color | Title active color | _string_ | - |
  | title-inactive-color | Title inactive color | _string_ | - |
  