perf：完善readme

index.js

@@ -1,9 +1,13 @@
 const Common = require('./src/utils/Common')
 const Storage = require('./src/utils/Storage')
+const crypto = require('./src/utils/Crypto')
+const SM4 = require('./src/utils/SM4')
 const HttpUtil = require('./src/https/HttpUtil')
 
 module.exports = {
     HttpUtil,
     Common,
     Storage,
+    SM4,
+    crypto,
 }