Adopt the OCaml Code of Conduct (#426)

Co-authored-by: ceastlund <50637515+ceastlund@users.noreply.github.com>
Co-authored-by: panglesd <peada@free.fr>
Co-authored-by: Sonja Heinze <sonjaleaheinze@gmail.com>
Signed-off-by: Thibaut Mattio <thibaut.mattio@gmail.com>

CHANGES.md

@@ -1,6 +1,8 @@
 unreleased
 ------------------
 
+- Adopt the OCaml Code of Conduct on the repo (#426, @pitag-ha)
+
 - Clean up misleading attribute hints when declared for proper context. (#425, @ceastlund)
 
 - Ast_pattern now has ebool, pbool helper, and a new map.(#402, @burnleydev1)

CODE_OF_CONDUCT.md

@@ -0,0 +1,13 @@
+# 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:
+
+- Sonja Heinze <sonja@tarides.com>
+- Paul-Elliot Anglès d'Auriac <peada@free.fr>
+- Carl Eastlund <ceastlund@janestreet.com>