feat: 维护ToC

Author: Guo-Zhang

.gitignore

@@ -0,0 +1,3 @@
+_build/
+.idea/
+.vscode/

README.md

@@ -0,0 +1 @@
+# Flutter教程

_toc.yml

@@ -1,6 +1,6 @@
 format: jb-book
 root: README.md
-chapter:
+chapters:
   - file: local_developing_tools/README.md
     sections: 
       - file: local_developing_tools/flutter_sdk_and_android_studio.md

widgets/slivers.md

@@ -1,17 +1,21 @@
 # Sliver组件
 
 教程：
--「Slivers in Flutter - Part (4)」- https://dhruvnakum.xyz/slivers-in-flutter-part-4 
-If you've used SafeArea then, SliverSafeArea is also doing the same thing except it takes 
-sliver as a child instead of Box widget.
+
+- [Slivers in Flutter - Part (4)](https://dhruvnakum.xyz/slivers-in-flutter-part-4)
+
+> If you've used SafeArea then, SliverSafeArea is also doing the same thing except it takes sliver as a child instead of Box widget.
 
 组件：
-- NestedScrollView: https://api.flutter.dev/flutter/widgets/NestedScrollView-class.html#widgets.NestedScrollView.1 
-- SliverOverlapAbsorber: https://api.flutter.dev/flutter/widgets/SliverOverlapAbsorber-class.html 
-- SliverAppBar: https://api.flutter.dev/flutter/material/SliverAppBar-class.html 
-- SliverToBoxAdapter: https://api.flutter.dev/flutter/widgets/SliverToBoxAdapter-class.html 
-- SliverPadding:  https://api.flutter.dev/flutter/widgets/SliverPadding-class.html 
+
+- [NestedScrollView](https://api.flutter.dev/flutter/widgets/NestedScrollView-class.html#widgets.NestedScrollView.1)
+- [SliverOverlapAbsorber](https://api.flutter.dev/flutter/widgets/SliverOverlapAbsorber-class.html)
+- [SliverAppBar](https://api.flutter.dev/flutter/material/SliverAppBar-class.html) 
+- [SliverToBoxAdapter](https://api.flutter.dev/flutter/widgets/SliverToBoxAdapter-class.html)
+- [SliverPadding](https://api.flutter.dev/flutter/widgets/SliverPadding-class.html)
 
 工具：
-- sliver_tools: https://pub.dev/packages/sliver_tools 
-- extended_sliver: https://pub.dev/packages/extended_sliver 
+
+- [sliver_tools](https://pub.dev/packages/sliver_tools)
+- [extended_sliver](https://pub.dev/packages/extended_sliver)
+