Add testing CLI changes guide to contributing.md

CONTRIBUTING.md

@@ -95,6 +95,52 @@ webapp:dev: If you didn't try to log in, you can safely ignore this email.
 ``
 4. Paste the magic link shown in your terminal into your browser to login.
 
+## Testing CLI changes
+To test CLI changes, follow the steps below:
+
+1. Build the CLI and watch for changes
+
+   ```
+   cd packages/cli
+   pnpm run dev
+   ```
+
+2. Open a new Terminal window and run the webapp locally and then create a new project in the dashboard. Copy out the dev API key.
+
+3. Create a new temporary Next.js app in examples directory
+
+   ```
+   pnpm create next-app@latest
+   ```
+
+   Follow the prompts to create a TypeScript project using the App Directory.
+
+4. Then once that's finished, add the `@trigger.dev/cli` to the `devDependencies` of the newly created Next.js app's `package.json` file, like so:
+
+   ```
+   {
+      "devDependencies": { "@trigger.dev/cli": "workspace:*" }
+   }
+   ```
+
+5. Open a new terminal window, navigate into the example, and initialize the CLI:
+
+   ```
+   cd examples/your-newly-created-nextjs-project
+   pnpm i
+   pnpm exec trigger-cli init
+   ```
+
+6. When prompted, select `self-hosted` and enter `localhost:3030` for your local version of the webapp. When asked for an API key, use the key you copied earlier.
+
+7. Run the CLI
+   ```
+   pnpm exec trigger-cli dev
+   ```
+
+8. After running the CLI, start your newly created Next.js project. You should now be able to see the changes.
+
+9. Please remember to delete the temporary project you created after you've tested the changes, and before you raise a PR.
 ## Add sample jobs
 
 The [examples/jobs-starter](./examples/jobs-starter/) project defines simple jobs you can get started with.