Update README.md

Closes #917

Author: ken-matsui

README.md

@@ -8,6 +8,9 @@
 
 ![](https://img.shields.io/badge/irc.libera.chat-%23poac%2C%23poac--dev-blue.svg)
 
+> [!IMPORTANT]
+> The information here may vary depending on the version you are using.  Please refer to the corresponding `README.md` by visiting the Git tag corresponding to your version, e.g., https://github.com/poac-dev/poac/blob/0.9.3/README.md.  Running `poac version` will provide you with the current version.
+
 ## Description
 
 > [!IMPORTANT]