version 0.7.0 added the column definitions table

• Added a setup vignette for how to download and install the package.
• Removed rcax_key(). Not needed. Cleaned up some {rredlist} refs.
• Added rcax_version() to print the installed versus GitHub version.
• Added cax_column_definitions from the definitions tab in the Excel files output by the HLI Tabular Query.
• type="colnames" now returns a data frame with a name and definition column.
• Added documentation for the internal data.
• Added RCMD check badge and workflow, did some minor cleanup to pass check.