[ftr] Add CITATION file

[daniel-jettka]

Is your feature request related to a problem? Please describe.
A CITATION file for providing basic metadata for publication, and giving credit to creators.
Could also be used for "About" page in Edirom-Online

Describe the solution you'd like
Add CITATION.cff file with important infos

[daniel-jettka]

Or some other basic metadata format which provides appropriate info.
Maybe edition overview could be fed automatically