Add generic guidance for return-after-catch

Given the code

```csharp
int Foo()
{
try
{
// try stuff
}
catch (Exception)
{
// catch stuff
}
return 0;
}
```

Advise that the return statement should be placed in the `try` block.

The same applies to `finally`, mutatis mutandis.

Obviously the `catch` or `finally` block must not occur within some conditional control flow and must occur as the final statement in the method.

I assume we have a generic test to ensure that `goto` is prohibited!