Rust

extended HashJoinExec docstring on build phase #667

Job	Run time
build with wasm-pack	1m 55s
Check cargo fmt	41s
cargo test (mac)	24m 36s
cargo check	5m 14s
Verify Vendored Code	47s
cargo test (win64)	3h 14m 12s
Verify MSRV	6m 14s
cargo test doc (amd64)	9m 24s
clippy	2m 10s
check configs.md is up-to-date	2m 12s
cargo doc	3m 5s
cargo test hash collisions (amd64)	8m 29s
cargo test (amd64)	9m 9s
cargo test datafusion-cli (amd64)	3m 18s
cargo examples (amd64)	6m 5s
Run sqllogictest with Postgres runner	3m 18s
cargo test pyarrow (amd64)	2m 13s
verify benchmark results (amd64)	9m 31s
check Cargo.toml formatting	1m 20s
	4h 53m 53s

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