Rust

Improve the documentation, the CI and fix Clippy #393

Job	Run time
Test the heed3 project (ubuntu-latest)	41s
Check the heed3 project (ubuntu-latest)	34s
Test the heed3 project (windows-latest)	1m 59s
Check all the features of the heed3 project (ubuntu-latest)	20s
Check the heed3 project (windows-latest)	2m 13s
Test the heed3 project (macos-latest)	36s
Check all the features of the heed project (ubuntu-latest)	7s
Check all the features of the heed3 project (macos-latest)	21s
Check the heed3 project (macos-latest)	21s
Check all the features of the heed project (macos-latest)	11s
Ensure clippy is happy on heed and heed3	23s
Ensure the heed and heed3 project are formatted	10s
Run the heed examples (ubuntu-latest)	7s
Run the heed3 examples (ubuntu-latest)	29s
Run the heed examples (macos-latest)	11s
Run the heed3 examples (macos-latest)	28s
Test the heed project (ubuntu-latest)	34s
Ensure heed3 is not erasing heed	3s
Test the heed project (windows-latest)	2m 43s
Test the heed project (macos-latest)	36s
	13m 7s

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