documented need an update for import @joakimono

[neonarc4]

https://codesandbox.io/p/sandbox/icy-butterfly-32kgcr?file=%2Fsrc%2Findex.js%3A14%2C26

import 'echarts-extension-leaflet';
incorrect mention in document
https://github.com/joakimono/echarts-extension-leaflet

[neonarc4]

@plainheart sorry about that comment x by my friend he dont know how to delete it so endup doing x