docs(sandboxes): document upload symlink behavior #1737

Job	Run time
Resolve PR metadata	9s
gpu-e2e	0s
e2e	0s
build-supervisor	0s
kubernetes-e2e	0s
build-gateway	0s
Core E2E result	-1s
GPU E2E result	-1s
Resolve PR metadata	7s
build-supervisor / Resolve build plan	2s
build-gateway / Resolve build plan	2s
build-supervisor / Rust sandbox (arm64) / sandbox (arm64)	3m 21s
build-supervisor / Rust sandbox (amd64) / sandbox (amd64)	3m 19s
build-gateway / Rust gateway (amd64) / gateway (amd64)	7m 18s
build-gateway / Rust gateway (arm64) / gateway (arm64)	7m 40s
build-supervisor / Build supervisor (amd64)	1m 30s
build-supervisor / Build supervisor (arm64)	1m 39s
build-supervisor / Merge supervisor manifest	1m 5s
build-gateway / Build gateway (amd64)	1m 25s
build-gateway / Build gateway (arm64)	1m 26s
gpu-e2e	0s
GPU E2E result	-1s
build-gateway / Merge gateway manifest	1m 3s
kubernetes-e2e / Kubernetes E2E (Rust smoke)	9m 22s
e2e / E2E (rust-docker)	7m 29s
e2e / E2E (rust-podman)	10m 18s
e2e / E2E (python)	6m 39s
Core E2E result	2s
	1h 3m 53s

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