Incorrect field label in API docs

[Jaydev Mahadevan]

In the time-series-chart options, the description indicates a time field should be used, but the example for the description uses a date field. The time field is the correct key.

[Michael Ratanapintha]

Fixed in commit 7d8af30 (#169) which should hopefully be officially released soon. Please feel free to ping us again if the release does not happen.