Schleuder: subscribers: make Cc examples more specific

Before, some examples would only list one email address, while in fact,
these examples talk about multiple email addresses.

schleuder/docs/subscribers.md

@@ -99,10 +99,10 @@ The resending-keywords must be included in messages sent to the normal list-addr
 **x-resend-cc:** someone@example.org anotherperson@example.org
 : Send one message to all of the given addresses in Cc, so they get to know of each other (encrypted if possible, otherwise in the clear).
 
-**x-resend-cc-encrypted-only:** someone@example.org
+**x-resend-cc-encrypted-only:** someone@example.org anotherperson@example.org
 : Send one message to all of the given addresses in Cc, so they get to know of each other, only if it could be encrypted to all of those addresses. Can be abbreviated to `x-resend-cc-enc.`
 
-**x-resend-cc-unencrypted:** someone@example.org
+**x-resend-cc-unencrypted:** someone@example.org anotherperson@example.org
 : Send one unencrypted message to all of the given addresses in Cc, so they get to know of each other. We skip looking for any key and will just send out the email in the clear.