Code of conduct: add links to the document's history and license notice

code-of-conduct.md

@@ -454,3 +454,13 @@ abusive behaviour, there are a number of ways you can ask for assistance or redr
   https://wiki.archlinux.org/index.php/ArchWiki:Maintenance_Team).
 - For the IRC channels: contact [one of the ops](
   https://wiki.archlinux.org/index.php/Arch_IRC_channels#Channel_operators).
+
+## About this document
+
+This code of conduct has been originally developed on the Arch wiki, where [its history](
+https://wiki.archlinux.org/index.php?title=Code_of_conduct&action=history) can be found. Later
+revisions of this document can be found in the [Arch Linux Service Agreements](
+https://gitlab.archlinux.org/archlinux/service-agreements) repository.
+
+The text is available under the terms of the [GNU Free Documentation License 1.3 or later](
+https://www.gnu.org/licenses/fdl-1.3.html).