Add debugger download troubleshooting to debugger.md #161

This add suggestions for troubleshooting download errors for the debugger
to debugger.md.

Author: gregg-miskelly

debugger.md

@@ -49,6 +49,13 @@ You can also find some example projects on https://github.com/aspnet/cli-samples
 ##### 2: Open the directory in VS Code
 Go to File->Open and open the directory in Visual Studio Code. If this is the first time that the C# extension has been activated, it will now download additional platform-specific dependencies.
 
+**Troubleshooting 'Error while installing .NET Core Debugger':** If the debugger is failing to download its platform-specific dependencies, first verify that you have the RC2 build of the .NET CLI installed, and it is functioning. You can check this by starting a bash/command prompt and running 'dotnet --info'. 
+
+If the CLI is installed, here are a few additional suggestions:
+
+* If clicking on 'View Log' doesn't show a log this means that running the 'dotnet --info' command failed. If it succeeds in bash/command prompt, but fails from VS Code, this likely means that your computer once had an older build of .NET CLI installed, and there are still remnants of it which cause VS Code and other processes besides bash to use the older version instead of the current version. You can try to clean your computer using the uninstall suggestions from http://dotnet.github.io/getting-started/.
+* If 'dotnet restore' is failing, make sure you have an internet connection to nuget.org, and make sure that if additional NuGet.Config files are being used, they have valid content. The log will indicate what NuGet.Config files were used. Try removing the files other than the one coming from the extension itself.
+
 ##### 3: Add VS Code configuration files to the workspace
 VS Code needs to be configured so it understands how to build your project and debug it. For this there are two files which need to be added -- .vscode/tasks.json and .vscode/launch.json.