docs(readme): update CLI usage with ESLint

readme.md

@@ -49,15 +49,7 @@ Note: Please read some important instructions regarding the `project` option [he
 
 There are [some more `parserOptions`](https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/parser/README.md#configuration) you may care about.
 
-If you're using ESLint v6 make sure you read about [the `--ext` command line option](https://eslint.org/docs/user-guide/command-line-interface#ext).
-
-Example command line usage for ESLint v6:
-
-```sh
-$ npx eslint --ext .js,.ts .
-```
-
-Example command line usage for ESLint v7:
+Example command line usage for ESLint v8:
 
 ```sh
 $ npx eslint .