Documentation update Pattern
Documentation update Pattern

Example codes added.

Closes https://github.com/dart-lang/sdk/pull/48005
https://github.com/dart-lang/sdk/pull/48005

GitOrigin-RevId: 7237529636f13def7069c5739376acff67462eb9
Change-Id: Ib41412f9a479b56868644370bf48c61ad3c71b8b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/225580
Reviewed-by: Lasse Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>
Commit-Queue: Lasse Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk