feat: add shared config all

Author: SchroederSteffen

README.md

@@ -13,9 +13,19 @@ npm install --save-dev eslint eslint-plugin-prefer-arrow-functions
 
 ### Flat
 
-For ESLint 9 and above.
+For ESLint 9 and above, use the shared config `all` in `eslint.config.mjs`:
 
-`eslint.config.mjs`:
+```js
+import pluginJs from '@eslint/js';
+import preferArrowFunctions from 'eslint-plugin-prefer-arrow-functions';
+
+export default [
+  pluginJs.configs.all,
+  preferArrowFunctions.configs.all,
+];
+```
+
+Or configure the rule(s) on your own:
 
 ```js
 import pluginJs from '@eslint/js';

src/index.ts

@@ -17,4 +17,14 @@ const plugin: TSESLint.FlatConfig.Plugin = {
   rules,
 };
 
+export const configs: TSESLint.FlatConfig.SharedConfigs = {
+  all: {
+    plugins: { 'prefer-arrow-functions': plugin },
+    rules: {
+      'prefer-arrow-functions/prefer-arrow-functions': 'warn',
+    },
+  },
+};
+plugin.configs = configs;
+
 export default plugin;