Credit Zurichess dataset and update readme

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84%. Comparing base (e9e607c) to head (dcfcbcd).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #253 +/- ## ===================================== Coverage 84% 84% ===================================== Files 34 34 Lines 4465 4465 Branches 4465 4465 ===================================== Hits 3723 3723 Misses 724 724 Partials 18 18 ```

[github-actions[bot]]

Against master [hash=256; threads=4]: 🆗 Elo difference: 20.87 +/- 39.57, LOS: 85.00 %, DrawRatio: 33.00 %

[github-actions[bot]]

Against v1.5.1 [hash=256; threads=4]: 🆗 Elo difference: 34.86 +/- 38.71, LOS: 96.15 %, DrawRatio: 36.00 %

[github-actions[bot]]

Against master [hash=64; threads=1]: 🆗 Elo difference: -6.95 +/- 17.30, LOS: 21.57 %, DrawRatio: 35.40 %

[github-actions[bot]]

Against v1.5.1 [hash=64; threads=1]: ✅ Elo difference: 40.13 +/- 17.93, LOS: 100.00 %, DrawRatio: 31.10 %