add type definitions to the npm package

Author: korompaiistvan

project/npm/package.json

@@ -20,6 +20,7 @@
     "license": "Apache-2.0",
     "author": "Vizzu Kft.",
     "main": "dist/vizzu.min.js",
+    "types": "dist/vizzu.d.ts",
     "repository": {
         "type": "git",
         "url": "https://github.com/vizzuhq/vizzu-lib.git"