Rust

Minor: Fix docs for JoinSet #70367

Job	Run time
linux build test	7m 26s
cargo test (macos-aarch64)	8m 46s
Verify Vendored Code	1m 20s
Check cargo fmt	1m 19s
build and run with wasm-pack	6m 52s
Verify MSRV (Min Supported Rust Version)	6m 18s
cargo check datafusion features	12m 39s
cargo check datafusion-proto features	5m 30s
cargo check datafusion-common features	1m 53s
cargo check datafusion-ffi features	2m 15s
cargo test (amd64)	18m 47s
verify benchmark results (amd64)	16m 21s
cargo check datafusion-functions features	2m 49s
clippy	8m 10s
check configs.md and ***_functions.md is up-to-date	7m 43s
check Cargo.toml formatting	3m 43s
cargo check datafusion-substrait features	12m 44s
cargo doc	5m 45s
check example README is up-to-date	6m 0s
cargo test doc (amd64)	10m 1s
cargo examples (amd64)	11m 52s
Run sqllogictest with Postgres runner	8m 58s
cargo test datafusion-cli (amd64)	5m 51s
Run sqllogictest in Substrait round-trip mode	9m 35s
	3h 2m 37s

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