chore: add generate-changelog to generate overall release notes (#218)

Author: AllanZhengYP

package.json

@@ -25,6 +25,7 @@
     "yargs": "^8.0.2"
   },
   "devDependencies": {
+    "generate-changelog": "^1.7.1",
     "jest": "^20.0.4",
     "lerna": "3.11.0",
     "typescript": "^3.0.0"