doc: dev: Continue contribution section.

doc/dev/documentation.org

@@ -282,8 +282,8 @@ Listing [[texlive-install]].
   sudo apt install texlive-full
 #+end_src
 
- Some org-mode configuration used in documentations files are define
-in =/doc/tools/=:
+Some org-mode configuration used in documentations files are define in
+=/doc/tools/=:
 - {{{file(PamhyrDoc.cls)}}}: The {{{latex}}} document class
 - {{{file(macro.org)}}}: Available macro
 - {{{file(latex.org)}}}: {{{latex}}} configutation for documentations
@@ -292,7 +292,53 @@ in =/doc/tools/=:
 - {{{file(ref.bib)}}}: Bibtex files for documentations files
 
 * TODO How to contribute?
-** TODO Contribution rules
+
+Pamhyr2 is free software: you can redistribute it and/or modify it
+under the terms of the GNU General Public License[fn:license], either
+version 3 of the License, or any later version.
+
+[fn:license] The GPLv3 web page:
+https://www.gnu.org/licenses/gpl-3.0.en.html
+
+** Guidelines
+
+To contribute to Pamhyr2, we expect a minimum of respect between
+contributors. We therefore ask you to respect the following rules
+regarding communication and contribution content:
++ No gender, racial, religious or social discrimination
++ No insults, personal attacks or potentially offensive remarks
++ Pamhyr2 is free software, and intended to remain so, so take care
+  with the licensing of libraries and external content you want to add
+  to the project
++ Humour or hidden easter eggs are welcome if they respect the
+  previous rules
+
+** Make a contribution
+
+There are several ways to contribute: you can report a bug by creating
+an issue on the project's gitlab page[fn:p2-gitlab], or you can create
+a merge request on the same page with the changes you have made to the
+code, translation or documentation.
+
+The Pamhyr2 copyright is owned by INRAE[fn:inrae], but we keep a
+record of each contributors. If you made a modification to pamhyr2
+software, please add your name at the end of {{{file(AUTHORS)}}} file
+and respect the Listing [[auth-format]] format. You can update this file
+information for following contribution.
+
+#+NAME: auth-format
+#+CAPTION: =AUTHORS= file format
+#+begin_src text
+<first name> <last name> [(optional) email], <organisation>, <years>
+#+end_src
+
+#+CAPTION: Current =AUTHORS= file
+#+INCLUDE: "../../AUTHORS" src text
+
+[fn:p2-gitlab] The Pamhyr2 Gitlab project page:
+https://gitlab.irstea.fr/theophile.terraz/pamhyr
+[fn:inrae] The INRAE web site: https://www.inrae.fr/
+
 ** TODO Translate
 ** TODO Code contribution