[thredds] [Support #RBW-315032]: netCDF-4 and the Enterprise Support Edition of HDF5

RE: The HDF Group's announcement of an Enterprise Support Edition

Unidata is evaluating ways to ensure ongoing support for HDF5-format data 
in netCDF, which will continue to be available to the community at no cost. We 
hope to be able to outline a way forward for netCDF shortly. 

For those who may have missed the announcement by the HDF Group yesterday, 
more details can be found here:

https://www.hdfgroup.org/2018/05/announcing-development-of-the-enterprise-support-edition-of-hdf5/

Cheers,

Unidata Support