接《篇2：Mapbox Style Specification》，继续解读Mapbox Style Specification。
目录
Spec Reference
官网文档地址：Spec Reference | Mapbox Style Spec | Mapbox Docs | Mapbox
style样式文件示例：
{
"version": 8,
"name": "{name}",
"metadata": "{metadata}",
"sources": "{sources}",
"sprite": "mapbox://sprites/{username}/{style_id}",
"glyphs": "mapbox://fonts/{username}/{fontstack}/{range}.pbf",
"layers": ["{layers}"],
"created": "2015
