Updated README

Signed-off-by: Andre Wanlin <awanlin@spotify.com>

plugins/devtools-backend/README.md

@@ -25,54 +25,6 @@ Here's how to get the DevTools Backend up and running in the new backend system:
 3. Now run `yarn start-backend` from the repo root
 4. Finally open `http://localhost:7007/api/devtools/health` in a browser and it should return `{"status":"ok"}`
 
-## Old Backend System
-
-If you are still on the old backend system, please consider migrating to the new backend system. But to install this plugin in an old backend, see below.
-
-1. First we need to add the `@backstage/plugin-devtools-backend` package to your backend:
-
-   ```sh
-   # From the Backstage root directory
-   yarn --cwd packages/backend add @backstage/plugin-devtools-backend
-   ```
-
-2. Then we will create a new file named `packages/backend/src/plugins/devtools.ts`, and add the
-   following to it:
-
-   ```ts
-   import { createRouter } from '@backstage/plugin-devtools-backend';
-   import { Router } from 'express';
-   import type { PluginEnvironment } from '../types';
-
-   export default function createPlugin(
-     env: PluginEnvironment,
-   ): Promise<Router> {
-     return createRouter({
-       logger: env.logger,
-       config: env.config,
-       permissions: env.permissions,
-       discovery: env.discovery,
-     });
-   }
-   ```
-
-3. Next we wire this into the overall backend router, edit `packages/backend/src/index.ts`:
-
-   ```ts
-   import devTools from './plugins/devtools';
-   // ...
-   async function main() {
-     // ...
-     // Add this line under the other lines that follow the useHotMemoize pattern
-     const devToolsEnv = useHotMemoize(module, () => createEnv('devtools'));
-     // ...
-     // Insert this line under the other lines that add their routers to apiRouter in the same way
-     apiRouter.use('/devtools', await devTools(devToolsEnv));
-   ```
-
-4. Now run `yarn start-backend` from the repo root
-5. Finally open `http://localhost:7007/api/devtools/health` in a browser and it should return `{"status":"ok"}`
-
 ## Links
 
 - [Frontend part of the plugin](https://github.com/backstage/backstage/tree/master/plugins/devtools)