models/github_reaction library

1. masamune_model_github package
2. documentation
3. models/github_reaction.dart

masamune_model_github package

1. Libraries
2. masamune_model_github
3. models/github_branch
4. models/github_commit
5. models/github_content
6. models/github_issue
7. models/github_issue_timeline
8. models/github_label
9. models/github_license
10. models/github_milestone
11. models/github_organization
12. models/github_project
13. models/github_pull_request
14. models/github_pull_request_head
15. models/github_pull_request_timeline
16. models/github_reaction
17. models/github_repository
18. models/github_repository_permission
19. models/github_user