This could work OK, but I still think that the cleanest solution is to keep the plugin documentation together in the same repository as the plugin code. That way if a new version of a plugin adds or removes or renames a parameter, or changes its meaning/purpose, the documentation will be automatically updated at the same time to match the code. Then the updated documentation will appear automatically in the MOD Duo UI as soon as the plugin is updated, so it will always correctly reflect the version of the plugin which is currently installed on the MOD Duo. That way there is no need to ignore the incomplete documentation right in front of you and follow a link to a different page to find the useful documentation.
In contrast if the code and the docs are in a different place, it’s far more likely that the docs will not be updated when the code changes. Also if you have a page per plugin in the wiki, then that page will have to document all versions of the plugin, which is hard to do cleanly.
Of course the downside is that it’s a bit trickier to change documentation in a source code repository, especially if it’s not hosted somewhere friendly like GitHub. But I think the extra effort would be worth it in the long run.