add nuget content to known issues

release-notes/2.0/2.0.0-known-issues.md

@@ -26,9 +26,20 @@ If the user does not have permissions to the dotnet directory when attempting to
 
 More info: [dotnet/docs/issues/2790](https://github.com/dotnet/docs/issues/2790) and [dotnet/cli/issues/7203](https://github.com/dotnet/cli/issues/7203)
 
-## NuGet disabled source are still used by dotnet.exe and msbuild
+## NuGet restore may treat disabled package sources as enabled in some cases
 
-[content TBD]
+**Issue:**
+The following restore command-line techniques treat disabled packages sources as enabled. NuGet#5704
+
+```
+msbuild /t:restore
+dotnet restore (either with dotnet.exe that ships with VS, or the one that comes with NetCore SDK 2.0.0)
+```
+
+**Workaround:**
+Use Visual Studio (2017 15.3 or later) or NuGet.exe (v4.3.0 or later)
+Delete your disabled source and continue to use msbuild or dotnet.exe.
+For your solution, you could use "Clear" in NuGet.config and then define the sources necessary for that solution.
 
 ## RHEL and the Runtime Package Store