Rust

Add/update doc strings #410

Job	Run time
Check cargo fmt	38s
cargo check	11m 24s
build with wasm-pack	3m 28s
Check License Header	2m 17s
cargo test (macos)	15m 57s
cargo test (macos-aarch64)	16m 4s
Verify MSRV (Min Supported Rust Version)	8m 52s
Verify Vendored Code	53s
cargo test (win64)	1h 10m 17s
clippy	1m 57s
check configs.md and ***_functions.md is up-to-date	3m 40s
check Cargo.toml formatting	2m 55s
cargo test hash collisions (amd64)	27m 42s
cargo doc	4m 15s
cargo test (amd64)	11m 51s
cargo test datafusion-cli (amd64)	4m 37s
cargo test doc (amd64)	17m 43s
cargo examples (amd64)	15m 13s
Run sqllogictest with Postgres runner	4m 11s
cargo test pyarrow (amd64)	2m 58s
verify benchmark results (amd64)	14m 8s
	4h 1m 0s

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