Documentation update for LinkedHashMap
Documentation update for LinkedHashMap

Added example code blocks for LinkedHashMap class and includes some minor textual updates to comments.

Closes https://github.com/dart-lang/sdk/pull/47706
https://github.com/dart-lang/sdk/pull/47706

GitOrigin-RevId: 86bded093f3304169aa97d7d6d0e64932ad184be
Change-Id: I8aa18dc04fb67498277c214916a3076428244a00
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/220301
Reviewed-by: Lasse R.H. 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