Update example turnserver.conf file to reflect that dh2066 is default

examples/etc/turnserver.conf

@@ -500,7 +500,7 @@
 #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>