Add commit rule sample for API package

[tanhongit]

Related https://github.com/cslant/blog-fe/issues/3 | https://github.com/cslant/blog-admin/issues/6

[tanhongit]

@hokhacminhtri please refer to this commit https://github.com/cslant/laravel-skeleton-package/tree/7e650b2a4a729682c7c7d96bed2f96426b7942cd