chore: instead of blacklisting with npmignore, not it is whitelisting in package.json with files

Author: WrathChaos

.npmignore

@@ -1,13 +1,17 @@
 {
   "name": "react-native-typescript-library-starter",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "description": "Extremely easy to create a React Native Component Library with both Stateful and Functional Component Examples.",
   "main": "./build/dist/index.js",
   "repository": "git@github.com:WrathChaos/react-native-typescript-library-starter.git",
   "author": "FreakyCoder <kurayogun@gmail.com>",
   "license": "MIT",
   "homepage": "https://www.freakycoder.com",
   "bugs": "https://github.com/WrathChaos/react-native-typescript-library-starter/issues",
+  "files": [
+    "/build",
+    "/lib"
+  ],
   "keywords": [
     "FreakyCoder",
     "freakycoder",