fix(typescript): declare types in package.json

Apparently this is needed for type resolution with "nodenext" module resolution.

fix #26

Author: djcsdy

package.json

@@ -14,6 +14,7 @@
   "bugs": "https://github.com/softwareventures/resolve-typescript-plugin/issues",
   "repository": "github:softwareventures/resolve-typescript-plugin",
   "license": "ISC",
+  "types": "index.d.ts",
   "scripts": {
     "fix": "tsc --noEmit && eslint . --fix && prettier --write .",
     "lint": "tsc --noEmit && eslint . && prettier --check .",