docs: update README and example with custom error page

Author: danielcondemarin

README.md

@@ -21,6 +21,7 @@ The plugin targets [Next 8 serverless mode](https://nextjs.org/blog/next-8/#serv
 - [Deploying a single page](#deploying-a-single-page)
 - [Overriding page configuration](#overriding-page-configuration)
 - [Custom page routing](#custom-page-routing)
+- [Custom 404 error page](#custom-404-error-page)
 - [Examples](#examples)
 
 ## Motivation
@@ -192,6 +193,22 @@ custom:
                     slug: true
 ```
 
+## Custom 404 error page
+
+By default, Amazon API Gateway returns 403 responses when a given route doesn't exist. Instead, the plugin renders the [\_error page](https://nextjs.org/docs/#custom-error-handling). That way you can customise how your 404 error page looks like.
+
+Simply add `pages/_error.js`:
+
+```js
+class Error extends React.Component {
+  render() {
+    return <p>404 page not found. (╯°□°)╯︵ ┻━┻</p>;
+  }
+}
+
+export default Error;
+```
+
 ## Examples
 
 See the `examples/` directory.

examples/basic-next-serverless-app/README.md

@@ -28,6 +28,10 @@ module.exports = {
 
 Alternatively, remove `assetPrefix` and the bucket won't be provisioned.
 
+#### Running locally
+
+`npx serverless offline`
+
 #### Deploy
 
 `serverless deploy`

examples/basic-next-serverless-app/package.json

@@ -27,6 +27,8 @@
   },
   "devDependencies": {
     "eslint-plugin-react": "^7.12.4",
-    "serverless-nextjs-plugin": "^1.1.2"
+    "serverless": "^1.39.1",
+    "serverless-nextjs-plugin": "^1.2.0",
+    "serverless-offline": "^4.9.2"
   }
 }

examples/basic-next-serverless-app/serverless.yml

@@ -10,6 +10,7 @@ region: eu-west-1
 
 plugins:
   - serverless-nextjs-plugin
+  - serverless-offline
 
 custom:
   serverless-nextjs: