block section from formatting

Hi,

I love the project thank you for doing it! :)

There is one feature I lack, for example in clang_format you can mark a section what the formatter shouldn't touch it looks like this:
```
// clang-format off
...
// clang-format on
```
In some cases I would love to do it.
Is there a way to do this in golines? Or do you think it could be added as a feature?

Thanks a lot!