add types export to package.json

Author: lzurbriggen

package.json

@@ -33,7 +33,8 @@
   "exports": {
     ".": {
       "require": "./dist/vue-haystack.cjs.js",
-      "import": "./dist/vue-haystack.es.js"
+      "import": "./dist/vue-haystack.es.js",
+      "types": "./dist/src/index.d.ts"
     },
     "./style.css": "./dist/style.css"
   },