Few arguments not documented in covidestim

[tamas-ferenci]

Parameters adapt_delta, max_treedepth and window.length of covidestim have no documentation under the Arguments.

[marcusrussi]

Thanks Tamas - adapt_delta and max_treedepth are arguments that are passed on to the function rstan::sampling, and we have modified them in the past for tuning purposes. We will be merging a major update to the model into master late next week, which will include documentation for these parameters, if still present.