Add a note on line-too-long to the formatter docs #20918

Job	Run time
cargo clippy	2m 42s
cargo test (linux)	5m 52s
cargo fuzz	6m 3s
cargo fmt	30s
cargo test (wasm)	2m 5s
cargo test (windows)	6m 48s
cargo udeps	2m 42s
Determine changes	11s
python package	1m 57s
test scripts	1m 2s
benchmarks	14m 47s
mkdocs	2m 10s
pre-commit	1m 55s
Formatter ecosystem and progress checks	0s
ecosystem	31s
test ruff-lsp	19s
	49m 34s

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