Fix docstring typo #700

Job	Run time
cargo test (windows-latest)	1m 37s
cargo test (macos-latest)	1m 1s
cargo clippy (windows-latest)	2m 30s
cargo check (msrv) (windows-latest)	1m 14s
cargo check (msrv) (android) (armv7-linux-androideabi)	42s
cargo test (ubuntu-latest)	38s
cargo clippy (macos-latest)	1m 0s
cargo check (msrv) (macos-latest)	29s
cargo check (msrv) (android) (aarch64-linux-android)	21s
cargo clippy (ubuntu-latest)	1m 2s
cargo check (msrv) (ubuntu-latest)	23s
cargo check (msrv) (android) (x86_64-linux-android)	42s
cargo clippy (android) (armv7-linux-androideabi)	59s
cargo clippy (android) (aarch64-linux-android)	1m 39s
cargo doc (windows-latest)	1m 24s
cargo clippy (android) (x86_64-linux-android)	1m 33s
formatting	21s
cargo doc (macos-latest)	26s
typos	4s
cargo doc (ubuntu-latest)	23s
	18m 28s

Provide feedback