refactor: update module paths and documentation for FIFO cache

[TKorr]

• Changed import paths in examples and tests to use the new cachekit::policy::fifo::FifoCache structure, enhancing clarity and consistency.
• Updated Cargo.toml to remove the outdated documentation link.
• Adjusted module documentation to reflect the addition of a release notes section, improving user awareness of changes.
• Incremented the eviction policy count in the documentation to accurately represent the current implementation.

Description

Related Issue

Fixes #

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 📝 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test addition or modification

How Has This Been Tested?

• Unit tests
• Integration tests
• Manual testing

Test environment:

• OS:
• Rust version:

Checklist

• My code follows the project's coding standards
• I have run cargo fmt and cargo clippy
• I have added tests for my changes
• All new and existing tests pass (cargo test)
• I have updated the documentation as needed
• I have added an entry to CHANGELOG.md (if applicable)

Screenshots (if applicable)

Additional Notes