Please document the undocumented properties in CSharpParseOptions

There are some properties on this class that appear as undocumented, but they are documented on the base class.

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#### Document Details

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* ID: 4ca0ca16-4554-ef3e-e18f-82a05fd1cbf5
* Version Independent ID: 89bb3e29-922b-a335-76cd-c257e250890e
* Content: [CSharpParseOptions.Features Property (Microsoft.CodeAnalysis.CSharp)](https://learn.microsoft.com/en-us/dotnet/api/microsoft.codeanalysis.csharp.csharpparseoptions.features?view=roslyn-dotnet-4.3.0#microsoft-codeanalysis-csharp-csharpparseoptions-features)
* Content Source: [dotnet/xml/Microsoft.CodeAnalysis.CSharp/CSharpParseOptions.xml](https://github.com/dotnet/roslyn-api-docs/blob/live/dotnet/xml/Microsoft.CodeAnalysis.CSharp/CSharpParseOptions.xml)
* Product: **dotnet-roslyn-api**
* Technology: **microsoft.codeanalysis**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**