Update C# wrapper (Namespace restructure, API additions, memory leak fix)

pkg/nuget/ZeroTier.Sockets/nuget.org.md

@@ -0,0 +1,29 @@
+[ZeroTier](https://www.zerotier.com) SDK
+=====
+
+Connect physical devices, virtual devices, and application instances as if everything is on a single LAN.
+
+ZeroTier brings your network into user-space. We've paired our network hypervisor core with a TCP/UDP/IP stack [(lwIP)](https://en.wikipedia.org/wiki/LwIP) to provide your application with an exclusive and private virtual network interface. All traffic on this interface is end-to-end encrypted between each peer and we provide an easy-to-use socket interface similar to [Berkeley Sockets](https://en.wikipedia.org/wiki/Berkeley_sockets). Since we aren't using the kernel's IP stack that means no drivers, no root, and no host configuration requirements.
+
+ - Website: https://www.zerotier.com/
+ - ZeroTier Manual: https://www.zerotier.com/manual/
+ - ZeroTier Repo: https://github.com/zerotier/zerotierone
+ - SDK Repo: https://github.com/zerotier/libzt
+ - Forum: https://discuss.zerotier.com
+
+## 1.3.3-alpha.2 Release Notes
+
+### New namespace structure:
+- `ZeroTier.Core` (API to control a ZeroTier Node)
+    - `class ZeroTier.Core.Node`
+    - `class ZeroTier.Core.Event`
+- `ZeroTier.Sockets`
+    - `class ZeroTier.Sockets.Socket`
+    - `class ZeroTier.Sockets.SocketException`
+- `ZeroTier.Central` (upcoming)
+
+### Added to Socket API
+ - `Socket.ReceiveTimeout`, `Socket.SendTimeout`, etc.
+
+### Bugs
+ - Fixed memory leak caused by unmanaged resources not being released.