chore: configure Renovate (#2)

* chore: add renovate.json

* chore(readme): update Renovate badge's link

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Pierre Cavin <[email protected]>

Author: renovate[bot]

README.md

@@ -3,7 +3,7 @@
 [![npm](https://img.shields.io/npm/v/@insurgentlab/commitlint-config)](https://www.npmjs.com/package/@insurgentlab/commitlint-config)
 [![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/insurgent-lab/commitlint-config/release.yml?branch=main)](https://github.com/insurgent-lab/commitlint-config/actions/workflows/release.yml)
 [![Codecov](https://codecov.io/gh/insurgent-lab/commitlint-config/branch/main/graph/badge.svg)](https://codecov.io/gh/insurgent-lab/commitlint-config)
-[![Renovate](https://img.shields.io/badge/renovate-enabled-brightgreen.svg)](https://github.com/insurgent-lab/commitlint-config/issues/5)
+[![Renovate](https://img.shields.io/badge/renovate-enabled-brightgreen.svg)](https://github.com/insurgent-lab/commitlint-config/issues/3)
 
 [conventional-changelog](https://github.com/conventional-changelog/conventional-changelog) preset built from a list of [conventional commit types](src/types.js) (similar to [conventional-commit-types](https://github.com/commitizen/conventional-commit-types)).
 Also provides [release rules](https://github.com/semantic-release/commit-analyzer#releaserules) configuration for [@semantic-release/commit-analyzer](https://github.com/semantic-release/commit-analyzer#releaserules).

renovate.json

@@ -0,0 +1,4 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["config:base"]
+}