Change the names of directories to respect one naming convention

[orazionelson]

Having one naming convention for language codes can help to build tool for automation and collaborative editing. I suggest to have all directories named with an underscore:

code_CODE

see also: https://groups.google.com/g/dataverse-community/c/t0-FtoSUU4o

[4tikhonov]

Thanks for fixing this, @orazionelson!