Follow-up: docs for confidential merge requests
### Problem to solve
Our documentation about confidential merge requests (moved to its own page in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/66494) lacks some useful info. The TW for ~"devops::create" (hi!) needs a correct answer from someone knowledgeable before any docs can be written.
### Further details
The questions remaining from confidential issue `https://gitlab.com/gitlab-org/gitlab/-/issues/334157`:
- **What do you do if you're not an Owner or Maintainer?** In the interest of MVC, https://docs.gitlab.com/ee/user/project/merge_requests/confidential.html acknowledges that you need to have one of these roles to create the private fork in a subgroup. What should users without those roles do?
- Is that item ^^ going to be "submit a patch"? If yes, what are the instructions for creating a patch? I found https://docs.gitlab.com/omnibus/development/creating-patches.html but I should check with someone if that's the right answer here.
- **Improving the experience for newer contributors:** How can we address this comment from @hadess1 in our documentation, to make it easier for new users to contribute fixes?
> "I didn't know how to ask collaborators on the original repo to review it, or how to get the fix branch automatically merged back into the original repository instead of the default branch of my fork."
### Proposal
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### Who can address the issue
Someone knowledgeable about creating confidential merge requests.
### Other links/references
- Related to confidential issue `https://gitlab.com/gitlab-org/gitlab/-/issues/334157` where questions were raised
issue