Using `climr_downscale` to acquire 1991-2020 averages of climate variables?

Hi, this is a great package you guys are working on and I'm really excited to start using it!

I'm interested in using the `climr_downscale` function to download the 1991-2020 average for MAP (mean annual precipitation) for a study area in BC (~679k locations in a 250m resolution DEM), but I'm a bit confused how to do this given the allowed arguments for `climr_downscale`. Looking at `?climr_downscale`, the `historic_period` argument seems promising, but calling `list_historic` shows the only period available is 2001_2020. Are other normals (i.e., 1991-2020) not available yet? I also tried using the `historic_ts` argument to download individual MAP rasters for 1991-2020, but had to kill the R process as memory consumption started to freeze my system.

Any guidance on using `climr_downscale` to acquire 30-year means of variables such as MAP would be very appreciated. Thank you!

Start with the ?climr_downscale documentation and the list_historic result to understand which historic periods are supported. Review how the historic_period and historic_ts arguments handle MAP data and large study areas. Done means determining whether 1991-2020 normals can be acquired and documenting or implementing a practical path without exhausting memory.

Written by the indexing model from the issue text.