Rust

Improve the documentation, the CI and fix Clippy #381

Job	Run time
Check the heed3 project (ubuntu-latest)	15s
Check all the features of the heed project (ubuntu-latest)	10s
Check the heed3 project (windows-latest)	2m 21s
Check all the features of the heed project (macos-latest)	13s
Check all the features of the heed3 project (ubuntu-latest)	18s
Check the heed3 project (macos-latest)	29s
Run the heed examples (ubuntu-latest)	27s
Check all the features of the heed3 project (macos-latest)	22s
Run the heed examples (macos-latest)	31s
Ensure the heed project is formatted	12s
Run the heed3 examples (ubuntu-latest)	18s
Ensure heed3 is not erasing heed	2s
Run the heed3 examples (macos-latest)	30s
Test the heed project (ubuntu-latest)	52s
Test the heed project (windows-latest)	53s
Test the heed project (macos-latest)	35s
	8m 28s

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