Update README files to include more information in the top level README #223

Job	Run time
Clang Tidy	9s
Clippy nightly (optional)	31s
Clippy	33s
Build+test (stable, ubuntu-24.04)	1m 53s
Build+test (stable, ubuntu-22.04)	1m 51s
Check for documentation errors	41s
Build+test (beta, ubuntu-24.04)	1m 48s
Format	16s
Miri	1m 5s
Build+test (beta, ubuntu-22.04)	1m 47s
Build+test (nightly, ubuntu-24.04)	1m 51s
Packaging	2m 47s
Build+test (nightly, ubuntu-22.04)	1m 42s
Valgrind	2m 9s
	19m 3s

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