官网英文资料：https://help.github.com/articles/connecting-to-github-with-ssh/
1、生成SSH keys文件id_rsa.pub
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
然后一直按回车键，直到显示成功完成
2、添加证书到电脑
ssh-add -K ~/.ssh/id_rsa
3、复制证书到github
#复制id_rsa.pub到粘贴板(clipboard)
pbcopy < ~/.ssh/id_rsa.pub
然后按照以下网址内的图片引导操作就完成了：
https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/