Add note about dependabot

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

README.md

@@ -21,6 +21,7 @@ ___
   * [inputs](#inputs)
   * [outputs](#outputs)
   * [environment variables](#environment-variables)
+* [Keep up-to-date with GitHub Dependabot](#keep-up-to-date-with-github-dependabot)
 * [Limitation](#limitation)
 
 ## Usage
@@ -119,6 +120,22 @@ The following [official docker environment variables](https://docs.docker.com/en
 |-----------------|---------|-------------|-------------------------------------------------|
 | `DOCKER_CONFIG` | String  | `~/.docker` | The location of your client configuration files |
 
+## 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"
+```
+
 ## Limitation
 
 This action is only available for Linux [virtual environments](https://docs.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners#supported-virtual-environments-and-hardware-resources).