Help text for identifiers

[MortenHofft]

Some guideline info-text on the format -- with/without HTTP would be useful.

Originally posted by @dagendresen in #415 (comment)

When filling in identifiers in the registry it would be nice to know which format is expected. This is useful in general but in particular for GrSciColl where we strive to have more editors.

@marcos-lg is it possible to specify on a general level? Or is it per type?

[dagendresen]

Maybe accept identifiers (ROR, Grid, Wikidata, etc) in both formats with HTTP part and without - and for the registry to automatically re-format before saving? (or simply recommend reporting the full format syntax including the http-part)