Fix docker turnserver.conf file comment about --dh2066

docker/coturn/turnserver.conf

@@ -488,7 +488,7 @@ pkey=/etc/ssl/private/privkey.pem
 #dh1066
 
 # Use custom DH TLS key, stored in PEM format in the file.
-# Flags --dh566 and --dh2066 are ignored when the DH key is taken from a file.
+# Flags --dh566 and --dh1066 are ignored when the DH key is taken from a file.
 #
 #dh-file=<DH-PEM-file-name>