[DOC] Add missing Monorepo configuration (#13253)

* [DOC] Add missing Monorepo configuration

* Update eslint/babel-eslint-parser/README.md

Co-authored-by: Federico Ciardi <fed.ciardi@gmail.com>

* [DOC] Unify monorepo config file

* [DOC] Clean monorepo configuration

* [DOC] Monorepo conf when eslint runned by package

Co-authored-by: Federico Ciardi <fed.ciardi@gmail.com>

eslint/babel-eslint-parser/README.md

@@ -91,6 +91,21 @@ module.exports = {
 };
 ```
 
+**Monorepo configuration**
+
+This configuration is useful for monorepo, when you are running ESLint on every package and not from the monorepo root folder, as it avoids to repeat the Babel and ESLint configuration on every package.
+
+```js
+module.exports = {
+  "parser": "@babel/eslint-parser",
+  "parserOptions": {
+    "babelOptions": {
+      "rootMode": "upward"
+    }
+  }
+}
+```
+
 ### Run
 
 ```sh