Updated card using information from data statement and datasheet
I updated and clarified the REFreSD [data card](https://github.com/mcmillanmajora/datasets/blob/refresd_card/datasets/refresd/README.md) with information from the Eleftheria's [website](https://elbria.github.io/post/refresd/). I added brief descriptions where the initial card referred to the paper, and I also recreated some of the tables in the paper to show relevant dataset statistics.

I'll email Eleftheria to see if she has any comments on the card. 