moving apidiff out of preview (#3595)

release-notes/3.0/api-diff/.Net/3.0.0_System.Net.Sockets.md

@@ -0,0 +1,44 @@
+# System.Net.Sockets
+
+``` diff
+ namespace System.Net.Sockets {
+     public enum AddressFamily {
++        ControllerAreaNetwork = 65537,
++        Packet = 65536,
+     }
+     public class NetworkStream : Stream {
++        public override int Read(Span<byte> buffer);
++        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken));
++        public override int ReadByte();
++        public override void Write(ReadOnlySpan<byte> buffer);
++        public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken));
++        public override void WriteByte(byte value);
+     }
+     public enum ProtocolFamily {
++        ControllerAreaNetwork = 65537,
++        Packet = 65536,
+     }
++    public sealed class SafeSocketHandle : SafeHandleMinusOneIsInvalid {
++        public SafeSocketHandle(IntPtr preexistingHandle, bool ownsHandle);
++        protected override bool ReleaseHandle();
++    }
+     public class SendPacketsElement {
++        public SendPacketsElement(FileStream fileStream);
++        public SendPacketsElement(FileStream fileStream, long offset, int count);
++        public SendPacketsElement(FileStream fileStream, long offset, int count, bool endOfPacket);
++        public SendPacketsElement(string filepath, long offset, int count);
++        public SendPacketsElement(string filepath, long offset, int count, bool endOfPacket);
++        public FileStream FileStream { get; }
++        public long OffsetLong { get; }
+     }
+     public class Socket : IDisposable {
++        public SafeSocketHandle SafeHandle { get; }
+     }
+     public enum SocketOptionName {
++        TcpKeepAliveInterval = 17,
++        TcpKeepAliveRetryCount = 16,
++        TcpKeepAliveTime = 3,
+     }
+ }
+```
+