Add a tip

Author: KSXGitHub

README.md

@@ -61,3 +61,5 @@ jobs:
 ```
 
 **Tip:** To create secrets (such as `secrets.AUR_USERNAME`, `secrets.AUR_EMAIL`, and `secrets.AUR_SSH_PRIVATE_KEY` above), go to `$YOUR_GITHUB_REPO_URL/settings/secrets`. [Read this for more information](https://help.github.com/en/actions/configuring-and-managing-workflows/creating-and-storing-encrypted-secrets).
+
+**Tip:** This action does not generate PKGBUILD for you, you must generate it yourself (e.g. by using actions before this action).