Add note about dependabot

Author: crazy-max

README.md

@@ -12,6 +12,18 @@ If you are interested, [check out](https://git.io/Je09Y) my other :octocat: GitH
 
 ![GitHub Labeler](.res/ghaction-github-labeler.png)
 
+___
+
+* [Usage](#usage)
+  * [YAML configuration](#yaml-configuration)
+  * [Workflow](#workflow)
+* [Customizing](#customizing)
+  * [inputs](#inputs)
+  * [environment variables](#environment-variables)
+* [Keep up-to-date with GitHub Dependabot](#keep-up-to-date-with-github-dependabot)
+* [How can I help?](#how-can-i-help)
+* [License](#license)
+
 ## Usage
 
 ### YAML configuration
@@ -102,7 +114,23 @@ Following environment variables can be used as `step.env` keys
 |----------------|--------------------------------------|
 | `GITHUB_TOKEN` | [GITHUB_TOKEN](https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token) as provided by `secrets` |
 
-## How can I help ?
+## Keep up-to-date with GitHub Dependabot
+
+Since [Dependabot](https://docs.github.com/en/github/administering-a-repository/keeping-your-actions-up-to-date-with-github-dependabot)
+has [native GitHub Actions support](https://docs.github.com/en/github/administering-a-repository/configuration-options-for-dependency-updates#package-ecosystem),
+to enable it on your GitHub repo all you need to do is add the `.github/dependabot.yml` file:
+
+```yaml
+version: 2
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+```
+
+## How can I help?
 
 All kinds of contributions are welcome :raised_hands:! The most basic way to show your support is to star :star2: the project, or to raise issues :speech_balloon: You can also support this project by [**becoming a sponsor on GitHub**](https://github.com/sponsors/crazy-max) :clap: or by making a [Paypal donation](https://www.paypal.me/crazyws) to ensure this journey continues indefinitely! :rocket: