[FEATURE] Add dock config variable to user_variables.lua

It would make sense to put a table into user_variables where a user can specify which widget he wants to use in which bar

The user then only has to put in strings representing each widget

e.g.

"Battery", "CPU_Temp" or "Taglist"

Bar = {
  screen_1 = {
    left_bar = {"Battery"},
    center_bar = {"Taglist"},
    right_bar = {"CPU_Temp"}
  },
  screen_2 = {
    left_bar = {"Battery"},
    center_bar = {"Taglist"},
    right_bar = {"CPU_Temp"}
  }
}

The init.lua in the crylia_bar folder would then take care of making sure the correct bar receives the correct widget.

Also update the docs after this is done and give a better explanation with examples.

Crylia / crylia-theme

[FEATURE] Add dock config variable to user_variables.lua #19