polkadot-sdk-docs: Use command_macro! #15084

Job	Run time
check-dependency-rules	8s
check-fail-ci	12s
check-markdown	13s
check-readme	2m 59s
check-workspace	17s
preflight / preflight	40s
preflight / ci-versions	1m 2s
test-rust-features	2m 23s
check-toml-format	1m 16s
check-umbrella	2m 34s
check-rust-feature-propagation	2m 12s
fmt	1m 46s
All quick checks passed	1s
	15m 43s

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