Update Hibernation Websocket Example (#25971)

This updates the example in several ways:
- Update the message contents so they are not the same in all cases.
- Remove closing WS connections from the sessions map

Author: zachlefevre

src/content/docs/durable-objects/examples/websocket-hibernation-server.mdx

@@ -131,24 +131,25 @@ export class WebSocketHibernationServer extends DurableObject {
 
     // Upon receiving a message from the client, the server replies with the same message, the session ID of the connection,
     // and the total number of connections with the "[Durable Object]: " prefix
-    ws.send(`[Durable Object] message: ${message}, from: ${session.id}. Total connections: ${this.sessions.size}`);
+    ws.send(`[Durable Object] message: ${message}, from: ${session.id}, to: the initiating client. Total connections: ${this.sessions.size}`);
 
     // Send a message to all WebSocket connections, loop over all the connected WebSockets.
     this.sessions.forEach((attachment, connectedWs) => {
-      connectedWs.send(`[Durable Object] message: ${message}, from: ${session.id}. Total connections: ${this.sessions.size}`);
+      connectedWs.send(`[Durable Object] message: ${message}, from: ${session.id}, to: all clients. Total connections: ${this.sessions.size}`);
     });
 
     // Send a message to all WebSocket connections except the connection (ws),
     // loop over all the connected WebSockets and filter out the connection (ws).
     this.sessions.forEach((attachment, connectedWs) => {
       if (connectedWs !== ws) {
-        connectedWs.send(`[Durable Object] message: ${message}, from: ${session.id}. Total connections: ${this.sessions.size}`);
+          connectedWs.send(`[Durable Object] message: ${message}, from: ${session.id}, to: all clients except the initiating client. Total connections: ${this.sessions.size}`);
       }
     });
   }
 
   async webSocketClose(ws: WebSocket, code: number, reason: string, wasClean: boolean) {
     // If the client closes the connection, the runtime will invoke the webSocketClose() handler.
+    this.sessions.delete(ws);
     ws.close(code, 'Durable Object is closing WebSocket');
   }
 }