You can now work on improving the phpList Manual by committing your changes directly to GitHub and open Pull Request to the new Manual Repository: https://github.com/phpList/phplist-manual
The first update has been made this Saturday, during the Bug Squash Party organized in Tirana, Albania. Elio Qoshi updated 16 of the images with screenshots from the Trevelin theme: https://github.com/phpList/phplist-manual/pull/1
Feel free to suggest your changes 
Thanks to @maltfield for pushing this project, and recently improving the Troubleshooting techniques section.
While merged PRs are automatically published to the web version of the manual, unfortunately the other formats are not yet automatically updated. That should be resolved in future once reliable scripts to do the conversion are identified.
This Github repository’s address URL seems outdated @Suela ?
The phpList manual has moved to a new place now. You can find it here:
https://www.phplist.org/manual/books/phplist-manual/
M
Ok, thanks to @mariana to reply,
if we would like to suggest a modification, then it should be done here?
Yes, you can create a new topic and explain what you would like to change and why.
M