Add comments to all justfile recipes #3589

Job	Run time
Test with MIME database	1m 54s
Output Regression Test	2m 29s
Test Linux (latest stable Rust)	1m 56s
Check Linux Packaging	1m 58s
Test x86_64-unknown-linux-gnu	2m 10s
Test x86_64-pc-windows-msvc	2m 8s
Test x86_64-unknown-linux-musl	2m 48s
Test aarch64-pc-windows-msvc	2m 20s
Test aarch64-unknown-linux-gnu	3m 27s
Rustfmt	18s
Test x86_64-apple-darwin	6m 5s
Actionlint	22s
Typo Check	10s
Test aarch64-apple-darwin	2m 30s
	30m 35s

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