Align dart_skills_lint with the example in dartlang

[reidbaker]

Add licence file, contribution guidelines, authors, changelog and add the repo link in the pubspec.
https://github.com/dart-archive/dartlang_project_templates/tree/main

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing tests are passing.

[gemini-code-assist]

Code Review

This pull request initializes the dart_skills_lint package by adding standard project files including AUTHORS, CHANGELOG, CONTRIBUTING, and LICENSE, and updating the pubspec.yaml with the repository URL. A formatting issue was identified in the AUTHORS file where an email address needs to be enclosed in angle brackets to match the file's instructions.

[gemini-code-assist]

The email address should be enclosed in angle brackets to match the format specified in the file's instructions (line 4).

Reid Baker <reidbaker@google.com>