Add information about NamedPipeServerStream's thread safety

### Type of issue

Missing information

### Description

Hello 👋 ,
Please consider adding information about thread safety on NamedPipeServerStream and related types. Since MS Docs is the source of truth for the .NET community, adding this information will help developers save time when implementing Named Pipes solutions.

Thank you!

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.io.pipes.namedpipeserverstream?view=net-8.0

### Content source URL

https://github.com/dotnet/dotnet-api-docs/blob/main/xml/System.IO.Pipes/NamedPipeServerStream.xml

### Document Version Independent Id

0daf4357-68d7-60eb-3e3e-5a7b7356071b

### Article author

@dotnet-bot