Update README.md

Author: nb312

README.md

@@ -8,7 +8,10 @@ This Demo contains contents as follow:
 - [Page view](#pageview)
 - [ListView](#listview)
 - [Slivers&CustomScrollView](#sliver)
+-[SliverPersistentHeader](#sliverpersistentheader)
 - [Nested ListView](#nestlistview)
+<img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/flutter_layout.gif" width="320">  
+
 ## RowColumn 
 > You can learn the layout of Row and Column.
 <img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/row_column.jpg" width="320">
@@ -33,6 +36,7 @@ This Demo contains contents as follow:
 ## ListView
 > Comply scrolling with Vertical and Horizontal.      
 <img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/list_screen_1.png" width="320">   <img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/list_screen_2.png" width="320">
+
 ## Sliver  
 Comply:
 - SliverGrid
@@ -41,6 +45,9 @@ Comply:
 - SliverFillViewport
 <img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/sliver_screen.png" width="320">
 
+## SliverPersistentHeader   
+<img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/hero_screen.png" width="320">
+
 ## NestListView
 > The child ListView nested in the parent ListView,I comply with two direction and you can change directions.   
 <img src="https://github.com/nb312/flutter_layout/blob/master/screenshots/nest_screen.png" width="320">