WebSocket.CloseStatus: Actual value is null when socket is open, not non-existent WebSocketCloseStatus.None

### Type of issue

Code doesn't work

### Description

[WebSocket.CloseStatus Property (8.0)](https://learn.microsoft.com/en-us/dotnet/api/system.net.websockets.websocket.closestatus?view=net-8.0) states, "If the close handshake has not been initiated yet, WebSocketCloseStatus.None is returned."

Actually, `WebSocketCloseStatus.None` does not exist. Before the close handshake begins, `CloseStatus` is `null`, as noted [in the field declaration](https://github.com/dotnet/runtime/blob/46c393aef810d1a4a3027fc208ae5414d2fdf2ce/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs#L85). (The actual [CloseStatus property](https://github.com/dotnet/runtime/blob/46c393aef810d1a4a3027fc208ae5414d2fdf2ce/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs#L289) just returns the backing field.)

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.net.websockets.websocket.closestatus?view=net-8.0

### Content source URL

https://github.com/dotnet/dotnet-api-docs-temp/blob/live/xml/System.Net.WebSockets/WebSocket.xml

### Document Version Independent Id

309b1648-c776-ccd8-f070-942978354273

### Platform Id

a928965b-7541-0003-9034-7d2e0789857b

### Article author

@karelz

Open the linked WebSocket.xml source and locate the CloseStatus property documentation. Compare its statement about the pre-handshake value with the linked ManagedWebSocket field and property references, then update the wording to describe the documented behavior accurately. Done means the API page no longer claims that WebSocketCloseStatus.None is returned.

Written by the indexing model from the issue text.