Added documentation about out-of-range components to DateTime.parse.
Added documentation about out-of-range components to DateTime.parse.

The [DateTime.parse](https://api.dart.dev/stable/2.10.4/dart-core/DateTime/parse.html) method accepts out-of-range components. For example, parsing the string "2020-01-42" produces "2020-02-11".

This was raised as a bug in https://github.com/dart-lang/sdk/issues/11189, but after more than 7 years that issue was closed with the solution being "use parseStrict from the intl package" instead.

This pull request simply **updates the documentation of DateTime's _parse_ method** so that users know:

1. This is how the method behaves. Otherwise they might be surprised when it unexpectedly happens in their code.
2. This behaviour is a feature and not a bug. Otherwise they might raise another issue for it.
3. The _parseStrict_ method in the intl package exists. Otherwise they might reinvent the wheel.

Closes https://github.com/dart-lang/sdk/pull/44521
https://github.com/dart-lang/sdk/pull/44521

GitOrigin-RevId: a88ada479d6664cac69a6dc44de3fe2a41f8e9be
Change-Id: Ic45e4db118bd3fad3a612659a35ca7a5d80937b4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/176680
Reviewed-by: Lasse R.H. Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>
Commit-Queue: Lasse R.H. Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>

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