Add reference to code of conduct

terms-of-service.md

@@ -75,6 +75,9 @@ or remove any content that, in our reasonable opinion, violates any Arch Linux
 policy or is in any way harmful or objectionable, or (iii) terminate or deny
 access to and use of the Services to any individual or entity for any reason.
 
+In addition, you agree to behave according to our Code of Conduct:
+https://wiki.archlinux.org/index.php/Code_of_conduct
+
 Responsibility of Visitors
 --------------------------
 
@@ -164,4 +167,4 @@ About This Document
 -------------------
 
 This document was derived from the Automattic Terms of Service and is licensed
-under a Creative Commons Sharealike license (CC BY-SA 4.0).
\ No newline at end of file
+under a Creative Commons Sharealike license (CC BY-SA 4.0).