Add CERTBOT_PLUGIN_PATH

README.md

@@ -22,6 +22,13 @@ Install this package via pip in the same python environment where you installed
 pip install certbot-dns-hetzner
 ```
 
+If `certbot plugins` does not show the newly installed plugin you might need to set `CERTBOT_PLUGIN_PATH`.  
+E.g.
+```
+CERTBOT_PLUGIN_PATH=/usr/local/lib/python3.9/site-packages/ certbot renew
+```  
+[Some background infos](https://community.letsencrypt.org/t/how-do-i-make-certbot-find-use-an-installed-plugin/198647/5)
+
 ## Usage
 
 To start using DNS authentication for the Hetzner DNS API, pass the following arguments on certbot's command line: