Link in "earning commit rights on an existing project" on "Contribute" page points to Committer Member page
https://www.eclipse.org/contribute/
IMHO, the link should be on "commit rights" instead of "existing project".
The link takes the user to the Committer Member page. There is content on that page titled "Becoming a Committer" which provides a good start, but it's framed in the context of becoming a committer member.
The handbook has some content on becoming a contributor and committer that, IMHO, is a better fit.