format navigation_and_routing README (#624)

navigation_and_routing/README.md

@@ -7,31 +7,34 @@ an article explaining Navigator 2.0.
 
 **Navigator 1.0 samples**
 
-* [nav_1/anonymous_routes.dart](lib/nav_1/anonymous_routes.dart) - Shows how to use a Navigator to push and pop
-  anonymous routes (e.g. MaterialPageRoute)
-* [nav_1/named_routes.dart](lib/nav_1/named_routes.dart) - Shows how to use define named routes via the `routes`
-  parameter on MaterialApp, and navigate using Navigator.pushNamed
-* [nav_1/on_generate_route.dart](lib/nav_1/on_generate_route.dart) - Shows how to handle arbitrary named routes
-  using the `onGenerateRoute` callback defined in the `MaterialApp` constructor.
+* [nav_1/anonymous_routes.dart](lib/nav_1/anonymous_routes.dart) - Shows how to
+  use a Navigator to push and pop anonymous routes (e.g. MaterialPageRoute)
+* [nav_1/named_routes.dart](lib/nav_1/named_routes.dart) - Shows how to use
+  define named routes via the `routes` parameter on MaterialApp, and navigate
+  using Navigator.pushNamed
+* [nav_1/on_generate_route.dart](lib/nav_1/on_generate_route.dart) - Shows how
+  to handle arbitrary named routes using the `onGenerateRoute` callback defined
+  in the `MaterialApp` constructor.
 
 **Navigator 2.0 samples**
 
-* [nav_2/pages.dart](lib/nav_2/pages.dart) - Shows how to define a list of [Page] objects on Navigator
-  declaratively.
-* [nav_2/router.dart](lib/nav_2/router.dart) - Full sample that shows a custom RouteInformationParser
-  and RouterDelegate parsing named routes and declaratively building the stack
-  of pages for the Navigator.
+* [nav_2/pages.dart](lib/nav_2/pages.dart) - Shows how to define a list of
+  [Page] objects on Navigator declaratively.
+* [nav_2/router.dart](lib/nav_2/router.dart) - Full sample that shows a custom
+  RouteInformationParser and RouterDelegate parsing named routes and
+  declaratively building the stack of pages for the Navigator.
 
 
 **Advanced**
 
-* [nav_2_advanced/nested_router.dart](lib/nav_2_advanced/nested_router.dart) - Shows two [RouterDelegate], one nested
-  within the other. A [BottomNavigationBar] can be used to select the route of
-  the outer RouterDelegate, and additional routes can be pushed onto the inner
+* [nav_2_advanced/nested_router.dart](lib/nav_2_advanced/nested_router.dart) -
+  Shows two [RouterDelegate], one nested within the other. A
+  [BottomNavigationBar] can be used to select the route of the outer
+  RouterDelegate, and additional routes can be pushed onto the inner
   RouterDelegate / Navigator.
-* [nav_2_advanced/transition_delegate.dart](lib/nav_2_advanced/transition_delegate.dart) - Shows how a custom
-  TransitionDelegate can be used to customized when transition animations are
-  shown.
+* [nav_2_advanced/transition_delegate.dart](lib/nav_2_advanced/transition_delegate.dart)
+  Shows how a custom TransitionDelegate can be used to customized when
+  transition animations are shown.
 
 
 ## Running