Request for clarification regarding OSCAR Schema v2 (schema-v2.md)

OSCAR Schema v2 found in docs/schema/schema-v2.md 
shows json files compressed into gz format.
my understanding is that OSCAR-2301 has moved to zstd format with the extension `.zst`

I think this should change to show files with .zst format or to merely mention that these files are compressed and
that this is just an example choice for compression.
