add postinstall

package.json

@@ -10,7 +10,8 @@
     "pre-push": "npm run pre-commit",
     "tslint": "tslint -c tslint.json 'types/**/*.d.ts' 'src/**/*.d.ts'",
     "tslint:fix": "npm run tslint -- --fix",
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "postinstall": "cd example && npm i"
   },
   "repository": {
     "type": "git",