build: automate adding of changelog

package.json

@@ -8,7 +8,7 @@
   },
   "scripts": {
     "build": "npm run tslint && npm run compile && npm run documentation",
-    "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s -r 0",
+    "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s -r 0 && git add CHANGELOG.md && git commit -m 'docs: update changelog'",
     "compile": "tsc && sed -i '1i#!/usr/bin/env node' lib/cli.js",
     "documentation": "typedoc --includeDeclarations --excludeExternals --mode modules --out docs src",
     "prepublishOnly": "npm run build",