Improve the README

## Do you have a favorite Git Resource?
Add it to the README!
If you need help, check out the Appendix in the training manual.

Open the repository's README and review the existing resource content. Check the Appendix in the training manual for guidance, then add a useful Git resource to the README. Done means the resource is included in the README in a clear, appropriate place.

由索引模型根据 Issue 内容生成。