docs: add note about permalink to installer

Author: finswimmer

docs/_index.md

@@ -51,6 +51,12 @@ using `get-poetry.py` should be uninstalled and reinstalled using `install.pytho
 in-place upgrades are possible.
 {{% /warning %}}
 
+{{% note %}}
+If you relying on a specific version of the installer script, it is recommended to replace the URL given in this
+documentation, by the [permalink](https://docs.github.com/en/repositories/working-with-files/using-files/getting-permanent-links-to-files)
+of the [script](https://github.com/python-poetry/install.python-poetry.org/blob/main/install-poetry.py) from the [repository](https://github.com/python-poetry/install.python-poetry.org).
+{{% /note %}}
+
 **Linux, macOS, Windows (WSL)**
 
 ```bash