Added ./src to the package

Author: Vlad Balin

package.json

@@ -4,7 +4,7 @@
   "description": "Reactive objects with transactional updates and automatic serialization",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
-  "files": [ "./dist" ],
+  "files": [ "./dist", "./src" ],
   "directories": {
     "test": "tests"
   },