I created a new "getting involved" document here:
It should cover all of the high level options. Some of the bullet points need additional documents expanding on them:
- Patch creation and submission - a straightforward document explaining how to create and submit patches in the format that we prefer. There is http://wiki.phpbb.com/Working_with_Git but it feels not quite right. There is also http://wiki.phpbb.com/Git which possibly duplicates some of the content. Ideally this page should contain enough information, and nothing irrelevant, that someone completely new to the project, and possibly to git, could submit a proper patch for a reasonably simple bug or enhancement. It should cover forking the repository on github, topic branches, proper commit messages, link to coding guidelines, pull request and associated tracker ticket.
- RFC process - I don't believe this is actually comprehensively documented in one place. When are RFCs needed, what stages they go through, etc.
Apparently I also created http://wiki.phpbb.com/Getting_Started a while ago, that still seems relevant but it is really a "getting started with modifying the code" which is one level below "get involved".
And the inventory of outdated/incorrect pages: