move row to suitable place, and improve comments. #575

Job	Run time
build with wasm-pack	2m 41s
cargo test (macos)	18m 45s
Check License Header	2m 45s
cargo check	7m 39s
cargo test (macos-aarch64)	13m 57s
Verify Vendored Code	54s
cargo test (win64)	1h 12m 27s
Check cargo fmt	40s
Verify MSRV (Min Supported Rust Version)	9m 7s
cargo test datafusion-cli (amd64)	4m 10s
cargo test (amd64)	12m 1s
cargo doc	2m 39s
clippy	6m 40s
cargo test hash collisions (amd64)	17m 47s
cargo test doc (amd64)	17m 25s
cargo examples (amd64)	14m 9s
Run sqllogictest with Postgres runner	3m 47s
cargo test pyarrow (amd64)	3m 7s
verify benchmark results (amd64)	14m 35s
check Cargo.toml formatting	3m 5s
check configs.md and ***_functions.md is up-to-date	3m 27s
	3h 51m 47s

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