keynest 0.4.0

Simple, offline, cross-platform secrets manager written in Rust
Documentation
## Description

<!-- Briefly describe what this PR does -->

## Type of change

- [ ] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Documentation update
- [ ] Refactoring

## Checklist

- [ ] I have tested my changes
- [ ] My code follows the project style guidelines
- [ ] I have updated documentation if needed
- [ ] I have added tests that prove my fix works

## Additional context

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