Adding alternative code snippets and unmaintained warning to readme

Author: jakejarvis

README.md

@@ -1,10 +1,31 @@
 # GitHub Action for Sleeping 💤
 
+## ⚠️ This action is unmaintained.
+
+> This action was published way back in the GitHub Actions beta and is largely abandoned now, mostly because there are much better ways to pause a job than building a whole Docker container on each run (which only works on Linux jobs, too). I highly recommend replacing this action with the following code snippets.
+>
+> On Linux and macOS runners, use [the `sleep` command](https://linux.die.net/man/1/sleep):
+>
+```yaml
+- name: Sleep for 30 seconds
+  run: sleep 30s
+  shell: bash
+```
+>
+> On Windows runners, use [the `Start-Sleep` command](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/start-sleep?view=powershell-7.1):
+>
+```yaml
+- name: Sleep for 30 seconds
+  run: Start-Sleep -s 30
+  shell: powershell
+```
+
+---
+
 This is a very, very simple (and small — only ~1.2 MB thanks to [`busybox`](https://hub.docker.com/_/busybox)) action to wait a specified amount of time before moving on in your workflow.
 
 Input follows the Linux `sleep` syntax for time units: a number followed by `s` for seconds, `m` for minutes, etc. [Man page for `sleep` here.](https://linux.die.net/man/1/sleep)
 
-
 ## Usage
 
 ```yaml
@@ -18,7 +39,6 @@ jobs:
         time: '30s'
 ```
 
-
 ## License
 
 This project is distributed under the [MIT license](LICENSE.md).