docs：更新文档

node_modules/postcss-modules/build/saveJSON.js

@@ -0,0 +1,14 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = saveJSON;
+
+var _fs = require("fs");
+
+function saveJSON(cssFile, json) {
+  return new Promise((resolve, reject) => {
+    (0, _fs.writeFile)(`${cssFile}.json`, JSON.stringify(json), e => e ? reject(e) : resolve(json));
+  });
+}