xilem: Docs updating #2540

Job	Run time
cargo check (aarch64-android)	27s
cargo check (msrv) (windows-latest)	1m 55s
cargo clippy (windows-latest)	5m 11s
cargo check (msrv) (wasm32)	21s
cargo check (msrv) (macos-latest)	40s
cargo clippy (macos-latest)	2m 9s
cargo clippy (wasm32)	1m 57s
cargo check (msrv) (ubuntu-latest)	51s
cargo clippy (ubuntu-latest)	3m 15s
cargo doc	50s
formatting	31s
Prime LFS Cache	4s
cargo test (wasm32)	23s
typos	7s
cargo test (windows-latest)	2m 44s
cargo test (macos-latest)	1m 54s
cargo test (ubuntu-latest)	3m 12s
	26m 31s

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