Add README for packages #295
Description
Parent issue: #252
- Add README for https://crates.io/crates/torrust-tracker-configuration
- Add README for https://crates.io/crates/torrust-tracker-primitives
- Add README for https://crates.io/crates/torrust-tracker-test-helpers
- Add README for https://crates.io/crates/torrust-tracker-located-error