#1626: change entry metadata tag names

The entry metadata in the CSV varies from the official list:

• In the CSV, greek is tagged as ge instead of el
• In the CSV, definition is tagged as def instead of df

greek should be el definition should be df

@matthewkumar, can you change the column names to match? Then, @NickLaiacona will be able to pull the values for List of Entries (https://edition640.makingandknowing.org/#/entries) related to https://github.com/cu-mkp/making-knowing-edition/issues/384

done