add themes and change initial theme

lua/kickstart/plugins/themes/kanagawa.lua

@@ -0,0 +1,12 @@
+return {
+  'rebelot/kanagawa.nvim',
+  lazy = false, -- make sure we load this during startup if it is your main colorscheme
+  priority = 1000, -- make sure to load this before all the other start plugins
+  config = function()
+    require('kanagawa').setup {
+      -- ...
+    }
+
+    vim.cmd 'colorscheme kanagawa'
+  end,
+}