Minor: Fixed regexpr_match docs #33753

Job	Run time
Check cargo fmt	40s
cargo check	6m 59s
build with wasm-pack	2m 35s
cargo test (macos)	10m 14s
cargo test (macos-aarch64)	9m 57s
Verify MSRV (Min Supported Rust Version)	8m 11s
Verify Vendored Code	55s
cargo test (win64)	1h 5m 33s
cargo test (amd64)	10m 42s
cargo test datafusion-cli (amd64)	3m 46s
clippy	5m 41s
cargo test hash collisions (amd64)	16m 58s
cargo doc	3m 54s
cargo test doc (amd64)	15m 47s
cargo examples (amd64)	13m 34s
Run sqllogictest with Postgres runner	3m 37s
cargo test pyarrow (amd64)	2m 46s
verify benchmark results (amd64)	12m 37s
check Cargo.toml formatting	2m 52s
check configs.md and ***_functions.md is up-to-date	3m 2s
	3h 20m 20s

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