Update to v2 of Contributor Covenant in shared GitHub repo (#7)

Author: j-f1

CODE_OF_CONDUCT.md

@@ -58,3 +58,10 @@ let timer = JSTimer(millisecondsDelay: 1000, isRepeating: true) {
     }
 }
 ```
+
+### Code of Conduct
+
+This project adheres to the [Contributor Covenant Code of
+Conduct](https://github.com/swiftwasm/.github/blob/main/CODE_OF_CONDUCT.md).
+By participating, you are expected to uphold this code. Please report
+unacceptable behavior to hello@swiftwasm.org.