https://blog.csdn.net/sky_jiangcheng/article/details/78248905
https://www.cnblogs.com/zjjDaily/p/8022944.html
外部: legend
饼图之上:
鼠标悬停:tooltip 默认:title(取自series的name) + name + value
饼图上每一部分:series >> itemStyle >> normal >> label【formatter+labelLine】 默认:name