Improve launch.json Documentation and Examples

Despite my best efforts, I haven’t been able to find any examples showing how to configure exception break-mode behavior on a per-exception basis. The Debug Adapter Protocol spec describes this under ExceptionOptions (https://microsoft.github.io/debug-adapter-protocol/specification#_exceptionoptions
), but the section is difficult to interpret in practice.

VS Code doesn’t appear to use the following configuration. Without examples that demonstrate the expected behavior, I can only guess whether this is correct.

```
{
"configurations": [
{
"name": "Launch App",
"type": "dotnet",
"request": "launch",
"exceptionOptions": [
{
"path": [
"System.OperationCanceledException"
],
"breakMode": "never"
}
]
}
]
}
```