docs: add Code of Conduct

Author: williamzujkowski

CODE_OF_CONDUCT.md

@@ -0,0 +1,20 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We pledge to make participation in our community a harassment-free experience for everyone.
+
+## Our Standards
+
+- Using welcoming and inclusive language
+- Being respectful of differing viewpoints
+- Gracefully accepting constructive criticism
+- Focusing on what is best for the community
+
+## Enforcement
+
+Instances of abusive behavior may be reported to the project maintainers.
+
+## Attribution
+
+Adapted from the [Contributor Covenant](https://www.contributor-covenant.org/), version 2.1.