Rust

Improve the documentation, the CI and fix Clippy #388

Job	Run time
Run the heed examples (ubuntu-latest)	39s
Check all the features of the heed3 project (ubuntu-latest)	16s
Run the heed examples (macos-latest)	22s
Check the heed3 project (ubuntu-latest)	25s
Check all the features of the heed3 project (macos-latest)	27s
Check all the features of the heed project (ubuntu-latest)	5s
Check the heed3 project (windows-latest)	2m 20s
Check all the features of the heed project (macos-latest)	12s
Check the heed3 project (macos-latest)	24s
Ensure the heed project is formatted	11s
Run the heed3 examples (ubuntu-latest)	28s
Run the heed3 examples (macos-latest)	23s
Ensure heed3 is not erasing heed	2s
Test the heed project (ubuntu-latest)	36s
Test the heed project (windows-latest)	2m 32s
Test the heed project (macos-latest)	35s
	9m 57s

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