BRA.csv population source update, and add population.R document

[estellad]

What type of PR is this?

Select all that apply: [ ] -> [x]

• [x] R
• [ ] other

R

I confirm:

• [ ] I followed the tutorial
• [ ] I checked the format with the ds_check_format function
• [ ] I double checked the data (e.g. coherent with google search)

Additional comments

Insert additional comments here...

[eguidotti]

Hi @estellad, thanks a lot for your PR!

• the script you used to update the csv file (population.R) is not needed. You can remote it from the PR
• the csv file BRA.csv should be placed in the folder inst/extdata/db (and not in the root directory)

I'm going to close this PR. It would be great if you can submit another one fixing the comments above. Many thanks!