Documentation update for Map class
Documentation update for Map class

Examples updated.

Closes https://github.com/dart-lang/sdk/pull/47782
https://github.com/dart-lang/sdk/pull/47782

GitOrigin-RevId: 98698d5b4d5b54acd2e317b6c426d7562d10ae2c
Change-Id: I0afff7c2977d81756f76ecda684c859021d57fd6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/221401
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