Add to documentation before making public

[Lewis-Barnett-NOAA]

Update readme:

• [x] adapt explanation of changes and key figures from output comparing old/new estimates
• [x] comment on how this relates to ROMS-based cold pool, linking to Kearney
• [x] showing how to access the data once the package has been installed
• [x] showing how folks to download the rda without installing the package
• [x] include brief info about the survey and data collection (emphasizing progression of stations over the season, how raw temp data are processed?)

When above is finished:

• [x] #21

[sean-rohan-NOAA]

@Lewis-Barnett-NOAA Updated the documentation. Didn't write too much about ROMS specifically, but included a suggestion for alternative temperature data sources and an explanation of why one would want to use them.

Seems like the package is pretty close to being ready to go public.

[Lewis-Barnett-NOAA]

@sean-rohan-NOAA I made some edits to the README. Looks great, thanks! I think we are ready to add Stan to the repo to provide review.