我自己总结的规范：
feature: 功能添加
bugfix: bug修复
change: 调整，比如配置，某些方法替换等
optimize: 优化过程
doc: 文档变更
refactor: 重构，功能不变
tests: 测试代码的调整
merge：分支合并
delete：分支删除
bugfix: ngx.ssl.session: avoided memory leaks when calling set_serialized_session repeatly. thanks spacewander for the patch.
optimize: corrected the initial table size of req socket objects. thanks spacewander for the patch.
doc: fixed a typo in a code comment. thanks Alex Zhang for the patch.
refactor: cleaned up some variable names and locals. thanks Thijs Schreijer for the patch.
tests: various changes in the test suite.
change: switched to SSL_version() calls from TLS1_get_version().
=================华丽的分割线==================
阮一峰的博客中推荐使用的git规范：http://www.ruanyifeng.com/blog/2016/01/commit_message_change_log.html
我自己用的话以自己的为准，阮一峰博客中的为辅。