fix: update doc arch

diagrams/ban.puml

@@ -0,0 +1,22 @@
+@startuml
+skinparam shadowing false
+title Control API: real address and ban of a player
+
+participant "Admin tool" as admin
+participant "etrelay control API\n<front-wg>:8090" as control
+participant "etrelay\nrelay loop" as relay
+participant "ET server" as et
+actor "Player\n203.0.113.7" as player
+
+note over admin, et : the ET server shows the player as <front-wg>:51234
+admin -> control : GET /sessions
+control --> admin : [{client: 203.0.113.7:27960, port: 51234}]
+note right of admin : port 51234 = 203.0.113.7
+
+== Ban ==
+admin -> control : PUT /bans/203.0.113.7\n{reason, minutes}
+control -> control : bans.json (atomic write)\ncut 203.0.113.7's sessions
+player -> relay : game packets
+relay -> relay : banned: dropped
+note over et : no packet: times the player out
+@enduml