Examples should be doc tests

[igaray]

• Both crates should have more examples in their READMEs,
• and examples more specific to the crate, and not duplicate the same example across the three READMEs
• and those READMEs should be included as the module docs for the crate root,
• and the examples should be doctests so as to run automatically in CI and break when the examples breaks.
• Ideally, the examples in the root README.md should also be doc tests