Update staging.md

docs/staging.md

@@ -10,6 +10,3 @@ To avoid this, please set the CA property to the Let’s Encrypt staging server
 ```bash
 CA="https://acme-staging.api.letsencrypt.org/directory"
 ```
-
-Please keep in mind that at the time of writing this letsencrypt.sh doesn't have support for registration management,
-so if you change CA you'll have to move your `private_key.pem` (and, if you care, `private_key.json`) out of the way.