Rust

Improve the documentation, the CI and fix Clippy #374

Job	Run time
Test the heed project (ubuntu-latest)	34s
Check all the features of the heed project (ubuntu-latest)	6s
Test the heed project (windows-latest)	36s
Check all the features of the heed project (macos-latest)	11s
Test the heed project (macos-latest)	40s
Run the heed examples (ubuntu-latest)	21s
Check the heed3 project (ubuntu-latest)	6s
Run the heed examples (macos-latest)	24s
Check all the features of the heed3 project (ubuntu-latest)	5s
Check the heed3 project (windows-latest)	2s
Check all the features of the heed3 project (macos-latest)	1s
Check the heed3 project (macos-latest)	1s
Ensure the heed project is formatted	12s
Run the heed3 examples (ubuntu-latest)	6s
Ensure heed3 is not erasing heed	4s
Run the heed3 examples (macos-latest)	1s
	3m 30s

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