npp data is incorrect in 01deg_jra55v140_iaf_cycle4 and 01deg_jra55v140_iaf_cycle4_jra55v150_extension

[aekiss]

As noted in hrsdawson/ACCESS-WOMBAT_01deg_BGC_validation#3 (comment), npp3d and related diagnostics (npp1, npp2d, npp_intmld, npp_int100) are in fact phytoplankton growth minus grazing, not npp (phytoplankton growth minus linear mortality).

This is easily fixed (see mom-ocean/MOM5#378), but we generated a lot of data with this incorrect formula in ACCESS-OM2-01 IAF cycle 4 and its extension (01deg_jra55v140_iaf_cycle4 and 01deg_jra55v140_iaf_cycle4_jra55v150_extension) so should the metadata for that be corrected to avoid confusion?

[aekiss]

Note @tylerrohr22's comment that pprod_gross could be regarded as net primary production because it is already net of autotrophic respiration.