CancellationToken in ISingleClientProxy.InvokeAsync is not optional

[SLjavad]

the CancellationToken parameter in InvokeAsync function is optional in Client Result section of document.
but it's not optional in real code

document :

please fix it

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Document Details

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• ID: 1387f556-b4b7-70f9-5bd0-f0bccc597689
• Version Independent ID: fb016cdc-d281-6b5b-7466-2c718e7274b4
• Content: Use hubs in ASP.NET Core SignalR
• Content Source: aspnetcore/signalr/hubs.md
• Product: aspnet-core
• Technology: aspnetcore-signalr
• GitHub Login: @bradygaster
• Microsoft Alias: bradyg

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Associated WorkItem - 65762

[Rick-Anderson]

ClientProxyExtensions.InvokeAsync shows it's required on each overload. @wadepickett move these embedded snippets to projects.

[BrennanConroy]

And don't use default or new CancellationToken(false) or CancellationToken.None in the docs.

[wadepickett]

Related: #28459 : Use hubs in SignalR: Move all code examples to app project vers 7.0

Related discussion I need to remember to review on dotnet/aspnetcore (development) 11542
"CancellationToken in the hub method signature is only supported for Server to client streaming currently."