Adopt OCaml Code of Conduct

This code of conduct lives in [ocaml/code-of-conduct](https://github.com/ocaml/code-of-conduct) and has been discussed in [this thread](https://discuss.ocaml.org/t/ocaml-community-code-of-conduct/10494).

It has been adopted by the OCaml compiler and many platform tools. After a discussion we propose adopting it for domainslib

Author: Sudha247

CODE_OF_CONDUCT.md

@@ -0,0 +1,14 @@
+# Code of Conduct
+
+This project has adopted the [OCaml Code of Conduct](https://github.com/ocaml/code-of-conduct/blob/main/CODE_OF_CONDUCT.md).
+
+# Enforcement
+
+This project follows the OCaml Code of Conduct
+[enforcement policy](https://github.com/ocaml/code-of-conduct/blob/main/CODE_OF_CONDUCT.md#enforcement).
+
+To report any violations, please contact:
+
+* KC Sivaramakrishnan <kc [at] tarides [dot] com>
+* Sudha Parimala <sudha [at] tarides [dot] com>
+* Vesa Karvonen <vesa [at] tarides [dot] com>