Make it easier to have multiple colorscheme plugins

lua/plugins/colorscheme.lua

@@ -1,4 +1,4 @@
-return {
+local kanagawa = {
   'rebelot/kanagawa.nvim',
   config = function()
     local kanagawa = require('kanagawa')
@@ -35,3 +35,5 @@ return {
     vim.cmd.highlight('link zshTodo Comment')
   end
 }
+
+return kanagawa