[examples/with-sentry] Better docs + correct dependencies (#6521)

examples/with-sentry/README.md

@@ -43,14 +43,22 @@ now
 
 ## About example
 
-This example show you how to add Sentry to catch errors in next.js
+An example showing use of [Sentry](https://sentry.io) to catch & report errors on both client + server side.
 
-You will need a Sentry DSN for your project. You can get it from the Settings of your Project, in **Client Keys (DSN)**, and copy the string labeled **DSN (Public)**.
+### Configuration
 
-The Sentry DSN should then be added as an environment variable when running:
+You will need a _Sentry DSN_ for your project. You can get it from the Settings of your Project, in **Client Keys (DSN)**, and copy the string labeled **DSN (Public)**.
+
+The Sentry DSN should then be added as an environment variable when running the `dev`, `build`, and `start` scripts in `package.json`:
 
 ```bash
-$ SENTRY_DSN=<dsn-here> npm run dev
+{
+  "scripts": {
+    "dev": "SENTRY_DSN=<dsn> node server.js",
+    "build": "SENTRY_DSN=<dsn> next build",
+    "start": "SENTRY_DSN=<dsn> NODE_ENV=production node server.js"
+  }
+}
 ```
 
-Note that if you are using a custom server, there is logging available for common platforms: https://docs.sentry.io/platforms/
+_Note: Setting environment variables in a `package.json` is not secure, it is done here only for demo purposes. See the [`with-dotenv`](../with-dotenv) example for an example of how to set environment variables safely._

examples/with-sentry/package.json

@@ -2,15 +2,16 @@
   "name": "with-sentry",
   "version": "1.1.0",
   "scripts": {
-    "dev": "node server.js",
-    "build": "next build",
-    "start": "next start"
+    "dev": "SENTRY_DSN=abc123 node server.js",
+    "build": "SENTRY_DSN=abc123 next build",
+    "start": "SENTRY_DSN=abc123 NODE_ENV=production node server.js"
   },
   "dependencies": {
     "@sentry/browser": "^4.6.1",
     "@sentry/node": "^4.6.1",
     "@zeit/next-source-maps": "0.0.4-canary.1",
     "cookie-parser": "1.4.4",
+    "express": "^4.16.4",
     "js-cookie": "2.2.0",
     "next": "latest",
     "react": "^16.8.0",