For GitHub, I looked at projects that interested me, but not necessarily having the skills to contribute code. So I would pour through the docs and find errors, typos, mistakes. These kinds of things. Cleaning up. Sometimes added documentation that was missing.
I think that exact job of documentation editor must exist somewhere. But definitely technical writing jobs exist. A lot are not remote but I think you can always ask about that even if it doesn't say that. The pandemic may have made them more flexible.
You can also contact agencies like Toptal and Robert Half.
If you want a different type of job then you need to have evidence or a convincing story that you have literally done that job before, either as an intern or through training/education or as projects on your own. But the fact that you have literally done proofreading and documentation editing in a technical context and there is a record on Github seems to be concrete proof that should be possible to leverage into getting paid work doing the same thing.
In the process of doing this type of work, you surely will learn new things and probably will help you figure out exactly what you might want to focus on / become an expert at / etc. You'll come to understand systems from a user's perspective which always good for developers.
As a software engineer, I'd love to see that someone is capable of putting effort into updating documentation, even with minor corrections and changes.
This is the kind of thing full time engineers typically don't enjoy doing, so docs stagnate and can quickly become out of date or inaccurate.
It's super useful if someone is used to a routine where they know how to dig into a project, find errors/inaccuracies, and work to improve them.
Fixing mistakes, typos, and errors are good things. Many articles and people suggest fixing typos in documentation for your first open source contributions. I would be interested if I found a new GitHub account with multiple accepted/pending PRs fixing things.
If they're presented as "I'm a code contributor" but it's solely non-code changes, then yes, it seems disingenuous at best.
But if they're accepted by the repo owner, they're probably not nonsense. And projects need better documentation. If the OP was applying for a junior 'tech' role of some sort, and demonstrated that experience of revising documentation to be up to date and improved... it's a step up from some people I've seen over the years (who leave behind bad/broken docs, for example).
