Your institution likely already has some web form or email address, attached to some type of internal workflow (¯\_(ツ)_/¯), for ingesting public feedback about the content or presentation of your collections information.
GitHub repositories have a light issue tracking system turned on by default, the idea being that any GitHub user can quickly post up an issue for review and discussion.
Do you want GitHub users to be able to post issues about content and formatting of the data themsevles?
Then you’ll need to make sure someone on your team is monitoring that new feedback channel.
If you want to funnel all feedback through a pre-existing email or web-form, say so explicitly in your README, and consider disabling GitHub issues on your repo.
You may also want to take a middle path: accept feedback about the GitHub repository and documentation itself via GitHub, but make sure that any data content/formatting issues go through your traditional submission process.
Again, just say so clearly under a specific heading in your README.