Update release notes.

Author: drieseng

build/nuget/SshNet.Security.Cryptography.nuspec

@@ -10,7 +10,7 @@
         <projectUrl>https://github.com/sshnet/Cryptography/</projectUrl>
         <requireLicenseAcceptance>false</requireLicenseAcceptance>
         <description>Cryptographic functions for .NET</description>
-        <releaseNotes>Added support for .NET Core (netstandard 1.0 and 1.3).</releaseNotes>
+        <releaseNotes>Added support for .NET Core 1.0 RC2 (.NETStandard 1.0 and 1.3).</releaseNotes>
         <summary>Cryptographic functions for .NET</summary>
         <copyright>2010-2016, RENCI</copyright>
         <language>en-US</language>