You can also contribute to the syslog-ng OSE documentation
The up-to-date syslog-ng Administration Guide received a new look and easier navigation, as well as better search experience. Best of all, you can now also easily contribute to the syslog-ng documentation.
Almost everything is available from the opening page at https://syslog-ng.github.io/
However, here are some direct links for you:
The syslog-ng 4.X documentation: https://syslog-ng.github.io/admin-guide/README
The syslog-ng documentation contributor guide: https://syslog-ng.github.io/doc-guide/README#how-to-contribute-to-the-documentation
The syslog-ng developer guide: https://syslog-ng.github.io/dev-guide/README (which still has some outdated parts)
And if you need the old syslog-ng 3.X documentation: https://www.syslog-ng.com/technical-documents/list/syslog-ng-open-source-edition/
If you find a problem in the documentation, you can report it at https://github.com/syslog-ng/syslog-ng.github.io/issues
You can read more about it at https://www.syslog-ng.com/community/b/blog/posts/you-can-also-contribute-to-the-syslog-ng-ose-documentation