[add] 补充Sliver系列的readme和screenshot

README.md

@@ -8,6 +8,7 @@ Flutter练习，欢迎Star，一起学习~
 - [Flutter滚动型容器组件 - ListView篇](https://github.com/SmallStoneSK/Blog/issues/13)
 - [Flutter网格型布局 - GridView篇](https://github.com/SmallStoneSK/Blog/issues/15)
 - [在Flutter中使用自定义Icon](https://github.com/SmallStoneSK/Blog/issues/14)
+- [在Flutter中创建有意思的滚动效果 - Sliver系列](https://github.com/SmallStoneSK/Blog/issues/18)
 
 ## 预览
 
@@ -24,4 +25,10 @@ Flutter练习，欢迎Star，一起学习~
   <img width="24%" src="./lib/grid_view/screen_shots/service_categories.png"/>
   <img width="24%" src="./lib/grid_view/screen_shots/programme_list.png"/>
   <img width="24%" src="./lib/custom_icon/screen_shots/antd_icons.png"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/sliverList-sliverGrid.gif"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/sliverAppBar-float.gif"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/sliverAppBar-snap.gif"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/sliverAppBar-pinned.gif"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/sticky-tabBar.gif"/>
+  <img width="24%" src="./lib/sliver_widgets/screen_shots/custom-sliver-header.gif"/>
 </div>

lib/sliver_widgets/README.md

@@ -0,0 +1,9 @@
+# CustomScrollView和Sliver系列 - 示例
+
+|1. [SliverList和SliverGrid](./basic_usage.dart)|2. [SliverAppBar float效果](./float_usage.dart)|3. [SliverAppBar snap效果](./snap_usage.dart)|
+|----|---|---|
+|<img width="265"  src="./screen_shots/sliverList-sliverGrid.gif"/>|<img width="265"  src="./screen_shots/sliverAppBar-float.gif"/>|<img width="265"  src="./screen_shots/sliverAppBar-snap.gif"/>|
+
+|4. [SliverAppBar pinned效果](./pinned_usage.dart)|5. [sticky吸顶效果](./sticky_usage.dart)|6. [自定义头部](./custom_sliver_header_usage.dart)|
+|----|---|---|
+|<img width="265" src="./screen_shots/sliverAppBar-pinned.gif"/>|<img width="265"  src="./screen_shots/sticky-tabBar.gif"/>|<img width="265"  src="./screen_shots/custom-sliver-header.gif"/>|