docs: Fix table in section "GET /api/v1.0/config"

If the number of columns doesn't agree between the rows,
the MarkDown table markup seems to be broken
and rendered incorrectly in both, the GitHub preview
and on https://deck.readthedocs.io/en/latest/API/#config.

Signed-off-by: Raphael Borun Das Gupta <git@raphael.dasgupta.ch>

Author: das-g

docs/API.md

@@ -1000,7 +1000,7 @@ Deck stores user and app configuration values globally and per board. The GET en
 
 #### Response
 
-| Config key | Description | Value |
+| Config key | Description |
 | --- | --- |
 | calendar | Determines if the calendar/tasks integration through the CalDAV backend is enabled for the user (boolean) | 
 | groupLimit | Determines if creating new boards is limited to certain groups of the instance. The resulting output is an array of group objects with the id and the displayname (Admin only)|