Keybinds go in a "keybinds" block and follow the format
<command> <modifiers> <keysym> <options>
But there's also a special "tag_bind" command that just takes modifiers
and one of set_output_tags, set_window_tags, toggle_output_tags, and
toggle_window_tags. It will automatically be used to loop through the
1-9 keys on tags 1<<0 to 1<<9, however, you can still implement those
commands individually if you want.