Fix `clippy::empty_line_after_doc_comments` lint #650

Job	Run time
cargo clippy (wasm32)	38s
cargo clippy (windows-latest)	1m 3s
cargo check (msrv) (windows-latest)	54s
cargo check (msrv) (wasm32)	19s
cargo clippy (macos-latest)	37s
cargo check (msrv) (macos-latest)	26s
cargo doc	23s
cargo clippy (ubuntu-latest)	41s
cargo check (msrv) (ubuntu-latest)	21s
cargo fmt	21s
cargo test (windows-latest)	52s
cargo test (wasm32)	17s
typos	5s
cargo test (macos-latest)	24s
cargo test (ubuntu-latest)	23s
	7m 44s

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