Improve some documentation for beginners #228

Job	Run time
Miri tests	3m 10s
Compile and test (ubuntu-latest, 1.60.0)	8m 40s
Compile and test (ubuntu-latest, stable)	5m 55s
Compile and test (ubuntu-latest, beta)	6m 59s
Compile and test (ubuntu-latest, nightly)	5m 56s
Compile and test (macos-latest, 1.60.0)	16m 41s
Compile and test (macos-latest, stable)	11m 35s
Compile and test (macos-latest, beta)	10m 8s
Compile and test (macos-latest, nightly)	13m 3s
Compile and test (windows-latest, 1.60.0)	9m 46s
Compile and test (windows-latest, stable)	7m 17s
Compile and test (windows-latest, beta)	7m 1s
Compile and test (windows-latest, nightly)	5m 31s
ci	1s
	1h 51m 43s

Provide feedback