cmd_swaynag_command: fix typo in variable
cmd_swaynag_command: fix typo in variable

The custom swaynag_command was being stored as config->swaybg_command
instead of config->swaynag_command.

ascent12/sway,ascent12/sway,1ace/sway,1ace/sway,ascent12/sway,SirCmpwn/sway,1ace/sway