save custom config

currently it's possible to save configuration values globally and per board. see https://deck.readthedocs.io/en/latest/API/#config

Now I want to save some custom values per board. For example type: "scrum"/"kanban" or globally "current board" : 2

For the background: I'm developing a mobile client for iOS and android. see here https://meltzow.github.io/deck-ng/
and I want to add some new features like board style or something like that. But I need a place where I can same some additional informations about the boards (or globally).

it will be perfect, if it possible to save some custom key-value-pair or some json. If some client (like your browser frontend) doesn't understand the additional values it will ignore them.

Start with the API configuration documentation linked in the issue and trace how global and per-board values are stored and exposed. Determine the extension point for custom key-value or JSON data, then define how clients that do not understand those values should handle them. Done means the requested board-level and global custom data can be saved and retrieved through the API without disrupting existing clients.