docs: fix wrong pushdown name & a typo #22118

Job	Run time
cargo check	7m 26s
build with wasm-pack	2m 20s
cargo test (win64)	45m 57s
cargo test (macos)	23m 30s
Check cargo fmt	43s
Verify MSRV	6m 5s
Verify Vendored Code	54s
cargo test (amd64)	11m 36s
cargo examples (amd64)	9m 12s
cargo test datafusion-cli (amd64)	3m 20s
cargo doc	3m 37s
cargo test doc (amd64)	12m 9s
Run sqllogictest with Postgres runner	2m 50s
cargo test pyarrow (amd64)	2m 23s
verify benchmark results (amd64)	9m 18s
check Cargo.toml formatting	1m 18s
clippy	4m 48s
check configs.md is up-to-date	2m 19s
cargo test hash collisions (amd64)	10m 38s
	2h 40m 23s

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