docs(tonic-build): Fix wrong hightlight #2481

Job	Run time
check (ubuntu-latest)	15s
cargo-deny check	27s
codegen	40s
check (macOS-latest)	28s
Interop Tests (ubuntu-latest)	39s
check (windows-latest)	22s
Interop Tests (macOS-latest)	51s
Check MSRV	56s
Interop Tests (windows-latest)	3m 6s
rustfmt	14s
test (ubuntu-latest)	3m 1s
Check unused dependencies (ubuntu-latest)	4m 24s
test (macOS-latest)	1m 45s
Check unused dependencies (macOS-latest)	3m 28s
test (windows-latest)	4m 45s
Check unused dependencies (windows-latest)	7m 45s
	33m 6s

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