Added NuGet shield

README.md

@@ -1,4 +1,5 @@
 # Discord.Net v1.0.0-rc
+[![NuGet](https://img.shields.io/nuget/vpre/Discord.Net.svg?maxAge=2592000?style=plastic)](https://www.nuget.org/packages/Discord.Net)
 [![MyGet](https://img.shields.io/myget/discord-net/vpre/Discord.Net.svg)](https://www.myget.org/feed/Packages/discord-net) 
 [![Build status](https://ci.appveyor.com/api/projects/status/5sb7n8a09w9clute/branch/dev?svg=true)](https://ci.appveyor.com/project/RogueException/discord-net/branch/dev)
 [![Discord](https://discordapp.com/api/guilds/81384788765712384/widget.png)](https://discord.gg/0SBTUU1wZTVjAMPx)