Update docs/setup.md

Co-authored-by: Tomoya Terashima <49265363+terassyi@users.noreply.github.com>

Author: p-strusiewiczsurmacki-mobica

docs/setup.md

@@ -33,7 +33,7 @@ Follow the instructions: https://kubectl.docs.kubernetes.io/installation/kustomi
 
 ## TLS certificates
 
-Coil runs an admission webhook server, and it needs a self-signed certificate. You can either generate certificates manually or have Coil create them when it starts up.
+Coil runs admission webhook servers, and each one needs a self-signed certificate. You can either generate certificates manually or have Coil create them when it starts up.
 
 ### Generate certificates manually