Clarify dependencies between metadata offered and displayed

As someone offering data to the viewer I'm kind of lost when it comes to the metadata. From the README I can guess, that the following information will be displayed at some point:

• the collection's collector
• the collection's title
• the collection's description

https://mrodzis.pages.gwdg.de/test/sampledata/collection.json offers all of these and the respective values are switched t o true, nevertheless the metadata panel is empty for all items.

See https://mrodzis.pages.gwdg.de/Qviewer/develop/#/.