master->main (#2779)

Author: pq

example/README.md

@@ -9,7 +9,7 @@ in the Dart ecosystem.
 
 The Dart team builds docs for the [Dart API reference](https://api.dart.dev/)
 with each new version of the SDK, via
-[this script](https://github.com/dart-lang/sdk/blob/master/tools/bots/dart_sdk.py).
+[this script](https://github.com/dart-lang/sdk/blob/main/tools/bots/dart_sdk.py).
 Look for `BuildDartdocAPIDocs`.
 
 ## Flutter

lib/src/experiment_options.dart

@@ -4,7 +4,7 @@
 
 ///
 /// Implementation of Dart language experiment option handling for dartdoc.
-/// See https://github.com/dart-lang/sdk/blob/master/docs/process/experimental-flags.md.
+/// See https://github.com/dart-lang/sdk/blob/main/docs/process/experimental-flags.md.
 ///
 library dartdoc.experiment_options;