Repo citation, list of authors, maintainer

[dsavchenko]

following discussion in https://github.com/oda-hub/oda-bot/pull/27

• We will need to support some form of citation file to refer to the repo itself and to external references. Preferably, it could be CITATION.cff
• The list of authors to cite is in citation. Do we need to use the list of authors from commits? E.g. for a list of mails to notify?
• We probably need to mark one of the authors as maintainer somewhere