Rust

add docs #16

Job	Run time
cargo check	2m 39s
Check cargo fmt	36s
build with wasm-pack	1m 56s
cargo test (mac)	14m 9s
Verify MSRV	6m 25s
Verify Vendored Code	45s
cargo test (win64)	27m 20s
cargo test hash collisions (amd64)	8m 37s
clippy	4m 28s
check Cargo.toml formatting	1m 16s
check configs.md is up-to-date	2m 19s
cargo doc	1m 45s
cargo test (amd64)	9m 4s
cargo test datafusion-cli (amd64)	3m 6s
cargo test doc (amd64)	9m 43s
cargo examples (amd64)	2m 14s
Run sqllogictest with Postgres runner	3m 6s
cargo test pyarrow (amd64)	2m 17s
verify benchmark results (amd64)	9m 47s
	1h 51m 32s

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