docs(container): document concrete path to gRPC ca.crt inside the image

[cidrblock]

Context

With the container default CMD using --grpc-tls, clients must trust the daemon CA. Docs refer to <runtime-dir>/tls/ca.crt but do not give the concrete in-container path (typically under /tmp/abbenay/tls/ when XDG_RUNTIME_DIR is unset) or a podman cp / volume-mount example.

Flagged during review of PR #63: #63

Proposal

• Add an explicit example path for the UBI image user
• Show podman cp <ctr>:/tmp/abbenay/tls/ca.crt ./ca.crt (or whatever path is correct after verifying)
• Cross-link from Python README container section

References

• PR fix(daemon): require TLS or --insecure for non-loopback gRPC (C2) #63
• docs/CONTAINER.md