Update vscode extension docs to say what to do with task output options on run

[rwarren]

Description

Having not used vscode tasks before I followed the Austin extension docs on profiling with tasks precisely.

However, when you go to execute the task you are presented with these options:

What to do here is not described in the extension docs! Choosing "Continue without scanning the task output" seems to work ok.

[P403n1x87]

@rwarren I think these messages are part of VS Code itself. Because the output from Austin (when run via the extension) wouldn't have any interesting error information, I think any option here would be fine. Perhaps there is a way for the extension to prevent this extra dropdown to appear. I'll look into it when I have some time.