update plugin readme

Author: mikeoliphant

StompboxPlugin/README.txt

@@ -15,3 +15,8 @@ VST3 path - usually "C:\Program Files\Common Files\VST3".
 **Important Note**: You must have .NET 8.0 or later installed:
 
 https://dotnet.microsoft.com/en-us/download/dotnet/8.0
+
+If you are still having trouble getting the plugin to work, please check out
+troubleshooting instructions here:
+
+https://github.com/mikeoliphant/StompboxUI/blob/master/StompboxPlugin/Troubleshooting.md