On Commons template and module pages we have /doc pages for documentation. I think we need those for the pages in Data namespace. We could document format, purpose of the page, and who is supposed to use it.
This would also be useful for adding a basic visualization of the data for some kinds of tabular data. For example, many of the Data talk: pages in https://commons.wikimedia.org/wiki/Category:Tabular_data_of_COVID-19_cases contain time series graphs of the case tables.