Adds an action command to a sign or block controlled by the ServerSigns plugin. Right-click the block after issuing this command to add the specified <action> to that block. The “add” command will actually automatically issue a “/serversigns create” command for you first if the right-clicked block has not been previously registered with the ServerSigns plugin.
The <action> parameter is the command that is to be run when a player right-clicks the sign and should include the initial “/” character. This command will then be invoked as if the player had entered the command themselves so will be constrained by whatever permission settings each player that uses the sign has.
Note that the ServerSigns plugin can only issue normal in-game Minecraft/Spigot/Paper commands. It is unable to invoke commands that need to be intercepted and processed by the Bungeecord/Waterfall/Velocity proxy software.