sync interpolateQueryStr and example docs

[Malinskiy]

Before commit 733474e the following used to work:

A = data('metric', filter=filter('tag', '[[tag_value_from_grafana_variable]]')).sum().publish(label='A')

Now since there is interpolation you shouldn't quote the variable which is not what the docs are suggesting.

A = data('metric', filter=filter('tag', [[tag_value_from_grafana_variable]])).sum().publish(label='A')

We should either fix the behaviour or change the examples in docs

[piotr-signalfx]

The changes should not affect single selection variables, please make sure both "Multi-value" and "Include All option" are disabled:

In case of multiple selection variables the previous implementation did not handle them whatsoever and hence the change.

I agree this behaviour should be described better in the docs.

[zerolaser]

@Malinskiy @piotr-signalfx Any progress on when this issue gets merged ?