Header of domain file getting added as a domain

[DDelbarre]

I was testing domain_mapping with a random JSON file from MetadataCatalogue, and decided to re-use the demo domain file (data-raw/domain_list_demo.csv). When domain_mapping loaded in the domain file it added the header row Domain_Name as one of the domains and was assigned code 5 (see screenshot below).

I think that either the template needs to be changed to remove the header row, or the code will need to be modified to exclude the header when it loads in a domain file.