Clippy: Fix `too_long_first_doc_paragraph` (#243) #735

Job	Run time
cargo clippy (gadget-core)	3m 45s
cargo clippy (gadget-common)	4m 38s
Rustfmt	16s
cargo clippy (blueprint-manager)	3m 23s
cargo test (gadget-core)	8m 20s
WASM checks	0s
cargo test (gadget-common)	7m 20s
cargo test (blueprint-manager)	11m 41s
	39m 23s

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