Re-add package.json main field for TypeScript support (#981)

Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

Author: mtdvlpr

package.json

@@ -51,6 +51,7 @@
     "read-dir-files": "^0.1.1",
     "standard": "^17.0.0"
   },
+  "main": "./lib/index.js",
   "exports": {
     ".": "./lib/index.js",
     "./esm": "./lib/esm.mjs"