What problem are you facing?

Looking at https://github.com/terraform-docs/terraform-docs/blob/master/README.md, it does not contain any information about the compatibility of this tool with OpenTofu. There is some information available if you search through the issues to find ones like #699, but this information should be available and summarized up front in the repo README.

How could terraform-docs help solve your problem?

Update the README to add a section about the current state of OpenTofu compatibility and support. https://terraform-docs.io/ should likely also provide this information.