Another way to find emails

[maelle]

Link to the package repo + https://www.nymeria.io/blog/how-to-manually-find-email-addresses-for-github-users so that if an author has committed to that repo, we use their commits to find their email address.

Related to #55

[maelle]

in hindsight we probably should only link to the package repo DESCRIPTION file

as the other method generates a few wrong email addresses.

[maelle]

so e.g. for https://github.com/ropensci/magick one would link https://github.com/ropensci/magick/blob/master/DESCRIPTION for author1 and author-others as often email addresses are stored in there so the table user would only need some copy-pasting.