Add .env.example

jest-puppeteer.config.js

@@ -1,8 +1,12 @@
 // jest-puppeteer.config.js
+require('dotenv').config()
+
+const port = process.env.PUPPETEER_PORT
+
 module.exports = {
   server: {
-    command: 'http-server ./www',
-    port: 8080,
+    command: `http-server --port ${port} ./www`,
+    port: port,
     launchTimeout: 5000
   },