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.