Update config.json docs

doc/shadowsocks-libev.asciidoc

@@ -167,7 +167,6 @@ The config file equivalent of command line options is listed as example below.
 | Command line                        | JSON
 | -s some.server.net                  | "server": "some.server.net"
 | -s some.server.net -p 1234 (client) | "server": "some.server.net:1234"
-| -p 1234 -k "PasSworD" (server)      | "port_password": {"1234":"PasSworD"}
 | -p 1234                             | "server_port": "1234"
 | -b 0.0.0.0                          | "local_address": "0.0.0.0"
 | -l 4321                             | "local_port": "4321"
@@ -186,6 +185,7 @@ The config file equivalent of command line options is listed as example below.
 | -u                                  | "mode": "tcp_and_udp"
 | -U                                  | "mode": "udp_only"
 | no "-u" nor "-U" options (default)  | "mode": "tcp_only"
+| (only in ss-manager's config)       | "port_password": {"1234":"PasSworD"}
 |============================================================================
 
 EXAMPLE