docs: add CODE_OF_CONDUCT.md

CODE_OF_CONDUCT.md

@@ -0,0 +1,26 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone.
+
+## Our Standards
+
+Examples of positive behavior:
+- Using welcoming and inclusive language
+- Being respectful of differing viewpoints
+- Gracefully accepting constructive criticism
+
+Examples of unacceptable behavior:
+- Trolling, insulting or derogatory comments
+- Public or private harassment
+- Publishing others' private information
+
+## Enforcement
+
+Instances of abusive behavior may be reported to project maintainers.
+
+## Attribution
+
+Adapted from [Contributor Covenant](https://www.contributor-covenant.org) v2.0.