Fix link to material spec (flutter#55416)

goderbauer · web-flow · commit e8a987e10869 · 2020-04-22T17:18:02.000-07:00
diff --git a/packages/flutter/lib/src/material/text_theme.dart b/packages/flutter/lib/src/material/text_theme.dart
@@ -32,7 +32,7 @@ import 'typography.dart';
 ///
 /// The Material Design typography scheme was significantly changed in the
 /// current (2018) version of the specification
-/// (https://material.io/design/typography).
+/// ([https://material.io/design/typography](https://material.io/design/typography)).
 ///
 /// The 2018 spec has thirteen text styles:
 /// ```
