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 README and review the Appendix in the training manual for context on the requested Git resource. Add a useful Git resource to the README; the change is done when it appears in the README in an appropriate location.

由索引模型根据 Issue 内容生成。