chore: add mergeDoc script

package.json

@@ -1,7 +1,7 @@
 {
   "name": "kaplay",
   "description": "KAPLAY is a JavaScript library that helps you make games fast and fun!",
-  "version": "3001.0.0-alpha.18.1",
+  "version": "3001.0.0-alpha.18.2",
   "license": "MIT",
   "homepage": "https://kaplayjs.com/",
   "repository": {
@@ -47,10 +47,11 @@
   "scripts": {
     "dev": "NODE_ENV=development node scripts/dev.js",
     "win:dev": "set NODE_ENV=development && node scripts/dev.js",
-    "build": "node scripts/build.js",
+    "build": "node scripts/build.js && npm run mergedoc",
     "check": "tsc",
     "fmt": "dprint fmt",
     "test": "node scripts/test.js",
+    "mergedoc": "dts-bundle-generator -o dist/doc.d.ts dist/declaration/index.d.ts",
     "test:vite": "vitest",
     "desktop": "tauri dev",
     "prepare": "npm run build",