At https://cs.opensource.google/go/x/mod/+/refs/tags/v0.5.0:sumdb/dirhash/hash.go;l=36, the Unix command equivalent given for Hash1() is

find . -type f | sort | sha256sum

which doesn't really capture what Hash1() actually does. It would be less misleading to give an equivalent like

find . -type f | sort | xargs sha256sum | sha256sum