[docs] README section about plugin development

README.md

@@ -5,6 +5,7 @@ Modular student club administration system, licensed under the MIT license.
 ## Installation
 
 ### Requirements
+
 ```
  "engines": {
     "node": ">= 12.22.1",
@@ -12,6 +13,7 @@ Modular student club administration system, licensed under the MIT license.
     "yarn": ">= 1.21.1"
  }
 ```
+
 So on debian (buster and bullseye) you will need to install node.js and yarn beside the debian packages to meet the needed versions.
 
 ```bash
@@ -23,11 +25,13 @@ npm i -g yarn
 npm i -g @quasar/cli
 popd
 ```
+
 ### Install the dependencies
 
 ```bash
 yarn install
 ```
+
 Be aware npm might not work.
 
 ### Configure Plugins
@@ -41,7 +45,7 @@ The application is using the API of [the backend](https://flaschengeist.dev/Flas
 This access needs to be configured in `src/config.ts'->config.baseURL
 
 - either you do have a proxy webserver that maps the '/api' to the backend (http://localhost:5000) or
-- you do directly configure the backend there:```baseURL: 'http://localhost:5000'```. Be aware not committing this configuration.
+- you do directly configure the backend there:`baseURL: 'http://localhost:5000'`. Be aware not committing this configuration.
 
 ### Build the application
 
@@ -76,15 +80,36 @@ yarn run lint
 
 #### Build a Plugin
 
-A Flaschengeist-Frontend-Plugin should be placed in `src/plugins`.
-It needs a `plugin.ts` File which exports a plugin with the following interface:
+Create a new node.js project and add `@flaschengeist/api` as a peer dependency (e.g. `yarn add --peer '@flaschengeist/api'`).
+If your plugin depends on an other plugin (e.g. you use the `@flaschengeist/users` plugin / stores),
+then you have to add that plugin as a peer dependency too.
 
-```
-name: string;
-mainRoutes?: PluginRouteConfig[];
-outRoutes?: PluginRouteConfig[];
-requiredModules: string[];
-version: string;
+You need to define a main entry point for your plugin (e.g. `"main": "src/index.ts"` in your `package.json`) which exportes
+a plugin descriptor as the default export (see `@flaschengeist/types` -> `FG_Plugin.Plugin`).
+E.g.
+
+```ts
+import { FG_Plugin } from '@flaschengeist/types';
+import { routes } from './routes';
+
+const plugin: FG_Plugin.Plugin = {
+  id: 'com.example.myplugin',
+  name: 'myplugin',
+  innerRoutes: routes,
+  // This are required backend plugins:
+  requiredModules: [['auth'], ['users'], ['roles']],
+  version: '0.0.1',
+  widgets: [
+    {
+      priority: 1,
+      name: 'greeting',
+      permissions: [],
+      widget: defineAsyncComponent(() => import('./components/Widget.vue')),
+    },
+  ],
+};
+
+export default plugin;
 ```
 
-You have to import `FG_Plugin` from `plugins.d.ts`.
+This will add a plugin providing a widget for the dashboard side and some routes.