chore(tvix/castore): move data model docs to here r/6920

These describe the castore data model, so it should live in the castore
crate.
Also, some minor edits to //tvix/store/docs/api.md, to honor the move of
the castore bits to tvix-castore.

Change-Id: I1836556b652ac0592336eac95a8d0647599f4aec
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9893
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

0 files changed, 0 insertions, 0 deletions