update documentation

README.md

@@ -0,0 +1,22 @@
+# FreeTube sync
+
+```mermaid
+sequenceDiagram
+    participant Client
+    participant Server
+
+    Note over Client, Server: Only once
+    Client->>+Server: Send initial history, playlists, profiles
+    Server-->>-Client: Response OK/KO
+
+    Note over Client, Server: Before launching FreeTube
+    Client->>+Server: Pull update to date history, playlists, profiles
+    Server-->>-Client: Response datas
+    Client->>+Client: Update databases
+
+    Note over Client, Server: While FreeTube is running
+    loop Watch local db updates
+        Client->>+Server: Send updated history, playlists, profiles
+        Server-->>-Client: Response OK/KO
+    end
+```

cmd/client/main.go

@@ -22,7 +22,7 @@ func main() {
 	case "pull":
 		pullcmd.Run()
 	default:
-		fmt.Print("You must pass a sub-command: init, watch")
+		fmt.Print("You must pass a sub-command: init, watch, pull")
 		os.Exit(1)
 	}
 }