[ArduinoLinkedList PR] Rewrite LinkedList README and sync metadata

This issue was forwarded from a pull request: braydenanderson2014/ArduinoLinkedList#2. <!-- mirror-source: braydenanderson2014/ArduinoLinkedList#2;type=pull_request --> Original pull request: https://github.com/braydenanderson2014/ArduinoLinkedList/pull/2 Opened by: @Copilot Base branch: main Head branch: braydenanderson2014:copilot/update-readme-and-changelog Draft: yes ### Source labels - (none) --- ### Original content ## Summary - rewrite the LinkedList README to better reflect the current public API - add a dedicated CHANGELOG.md for release history - align versioned metadata and stale documentation links in the mirror repository - open this mirror PR so the existing forwarding workflow can keep `braydenanderson2014/C-Arduino-Libraries` in sync ## Validation - secret scanning passed for the updated files - parallel validation completed successfully - local `arduino-lint` execution was attempted, but the current public CLI no longer accepts the workflow's `--official` flag and the Library Manager index download was blocked by network resolution in this environment