Document tarzstd as an argument for CACHE_COMPRESSION_FORMAT
Problem to solve
In !4107 (merged), tarzstd support was added as a valid value for CACHE_COMPRESSION_FORMAT. However, this is not documented anywhere.
Further details
If no one knows this exists, I suppose most people won't try out this option.
Proposal
Document that tarzstd support was added as a valid value for CACHE_COMPRESSION_FORMAT.