Add note about @master in readme

Author: Tyrrrz

readme.md

@@ -21,6 +21,10 @@ jobs:
           url: https://example.com
 ```
 
+> **Note**:
+> When referencing the action, replace `@master` above with either the latest release tag or a specific commit hash.
+> You can consult with this [article](https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions) for more information.
+
 ### Advanced example
 
 ```yaml