post https://api.miro.com/v2/boards//items/
Attach an existing tag to the specified item. Card and sticky note items can have up to 8 tags.
Note: Updates to tags made via the REST API will not be reflected on the board in realtime. To see REST API updates to tags on a board, you need to refresh the board. This applies to the following endpoints: Remove tag from item, Update tag, Delete tag.