Update postgresql.conf line for default superuser_reserved_connections.

src/backend/utils/misc/postgresql.conf.sample

@@ -59,7 +59,7 @@
 # Note: increasing max_connections costs ~400 bytes of shared memory per 
 # connection slot, plus lock space (see max_locks_per_transaction).  You
 # might also need to raise shared_buffers to support more connections.
-#superuser_reserved_connections = 2	# (change requires restart)
+#superuser_reserved_connections = 3	# (change requires restart)
 #unix_socket_directory = ''		# (change requires restart)
 #unix_socket_group = ''			# (change requires restart)
 #unix_socket_permissions = 0777		# octal