Multiple Tools (Documentation): Format of --arguments_file

[J-Moravec]

--argument_file is a parameter shared by many tools.

It allows providing arguments in a file instead on a command line, which is very convenient when e.g., merging multiple files using CombineGVCFs.

And yet, the format of the argument_file is not mentioned anywhere.

Compare with the --sample-name-map from GenomicDBImport which mentions tab-delimited format for this file.
Some guidance like this for the argument_file would be useful.