docs: add community code of conduct

CODE_OF_CONDUCT.md

@@ -0,0 +1,61 @@
+# Code of Conduct
+
+## Our commitment
+
+The shadowsocks-c community welcomes people of all backgrounds and experience
+levels. Everyone should be able to participate without harassment, regardless of
+age, disability, ethnicity, gender identity or expression, nationality, personal
+appearance, race, religion, sexual orientation, or socioeconomic status.
+
+## Expected behavior
+
+- Treat others with respect and consideration.
+- Give constructive feedback about ideas and code, and accept feedback graciously.
+- Assume good intentions while taking responsibility for the impact of your words
+  and actions.
+- Welcome newcomers, respect differing perspectives, and help keep discussions
+  focused on the project.
+- Respect people's privacy and their requests to stop unwanted contact.
+
+## Unacceptable behavior
+
+- Harassment, discrimination, threats, or intimidation.
+- Personal attacks, insults, trolling, or deliberately disruptive behavior.
+- Sexualized language or imagery, and unwelcome sexual attention or advances.
+- Sharing someone's private information without their explicit permission.
+- Retaliation against anyone who reports a concern or participates in an
+  investigation.
+
+## Scope
+
+This code applies in project spaces, including issues, pull requests, discussions,
+and other communication channels maintained by the project. It also applies when
+someone officially represents the project in public spaces or at events.
+
+## Reporting
+
+Report violations privately to Max Lv at
+[max.c.lv@gmail.com](mailto:max.c.lv@gmail.com). Include a description of what
+happened, relevant links or screenshots when available, and any immediate
+concerns. You do not need to confront the person involved before reporting.
+
+If your report involves that maintainer, contact Linus Yang at
+[linusyang@gmail.com](mailto:linusyang@gmail.com) instead. A maintainer involved
+in a report should not decide its outcome.
+
+Please avoid posting reports or private details in public issues. Reports will
+be reviewed fairly and handled as confidentially as possible, with information
+shared only as needed to investigate and respond.
+
+## Enforcement
+
+Maintainers may edit or remove contributions that violate this code and will
+consider the severity, impact, and history of the behavior when responding.
+Responses may include a request to stop or correct the behavior, a warning, a
+temporary restriction on participation, or a permanent ban. Serious violations
+may result in an immediate ban without a prior warning.
+
+When practical, maintainers will explain the action and its reason privately to
+the person affected. Anyone seeking reconsideration may contact an uninvolved
+maintainer through the reporting contacts above and provide additional context.
+Maintainers are expected to follow this code themselves and apply it consistently.

README.md

@@ -13,6 +13,11 @@ created by [@clowwindy](https://github.com/clowwindy), and maintained by
 
 Current version: 3.3.6 | [Changelog](debian/changelog)
 
+## Community
+
+Everyone participating in this project is expected to follow our
+[Code of Conduct](CODE_OF_CONDUCT.md).
+
 ## Project history and rename
 
 This repository began as **shadowsocks-libev**, the lightweight C implementation