feat: docs + dependency updates

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Documentation

• update README and lib.rs for better documentation of existing features.
• add full feature flag and update github worklow; fix default feature flag.
• add examples/borrow-instead-of-move to document how to use references instead of moving a value.
• move contribution guidelines into its own file CONTRIBUTING.md.
• fix tests and examples

Dependency

• don't pin dependencies to allow allow minor or patch updates in all crates including examples: closes Unpin Major Crate Deps #327