Added DevTools plugin

Signed-off-by: Andre Wanlin <67169551+awanlin@users.noreply.github.com>

plugins/devtools-backend/README.md

@@ -0,0 +1,56 @@
+# DevTools Backend
+
+Welcome to the DevTools backend plugin! This plugin provides data for the [DevTools frontend](../devtools/) features.
+
+## Setup
+
+Here's how to get the DevTools Backend up and running:
+
+1. First we need to add the `@backstage/plugin-devtools-backend` package to your backend:
+
+   ```sh
+   # From the Backstage root directory
+   cd packages/backend
+   yarn 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,
+     });
+   }
+   ```
+
+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](../devtools/README.md)
+- [The Backstage homepage](https://backstage.io)