[v3] Add credits file to track and each exercise #305
Description
We should add .meta/CITATION.bib files to each exercise and the track repo so that people who may want to use exercise for their own workshops, classes etc. have an easy way of giving credit in the same way that one can easily cite used Julia packages that contain a CITATION.bib file.
The files should be (semi-)automatically generated from the contributor information in .meta/config.json, ideally as part of CI runs.
(cc @exercism/julia)