Blimpy documentation needs an update

[texadactyl]

There are 2 new command line utilities (calcload and rawhdr). Also, the existing capability is lacking in clarity or simply missing in the docs.

[tstellanova]

Making a note to update the voyager example (and other) references to gpuspec to rawspec as per @david-macmahon it sounds like rawspec is the tool mostly/currently used to generate HDF5 (or filterbank) files. (I'm unclear whether/how gpuspec is still used currently, possibly it's still used for one-off conversions outside of the main data pipeline.)

[david-macmahon]

For some historical context, gpusepc was the original CUDA implementation that inspired (and was ultimately supplanted by) rawspec.