Documentation update needed

[apull]

When trying to import Contributions to Rock 13.7 using Bulldozer 1.13.7.1.20230329, I get an error about index exceeding array size. By checking with the sample files, I assumed that SourceType is a required field for the import file, but the documentation does not list that column. When this was added to my file, import worked properly. Please update the .csv documentation.