map_functions_to_docs: Map all Rd files to the functions they describe
Description
adapted from mpn.scorecard
Usage
map_functions_to_docs(exports_df, pkg_source_path, verbose)
Value
Returns the data.frame passed to `exports_df`, with a `documentation`
column appended. This column will contain the path to the `.Rd` files in
`man/` that document the associated exported functions.