Add file type description to HDFParsers

gostep explains that, there are three versions of NetCDF (classic format, 64-bit offset, and netCDF-4/HDF5 format). When opening an existing netCDF file, the netCDF library will transparently detect its format so we do not need to adjust according to the detected format.

That said, it would be good to know the file type as each can have the .nc extension. This will add patch with add file type to the metadata.