feat(plugins): setup gruvbox colorscheme.

lua/plugins/colorscheme.lua

@@ -0,0 +1,12 @@
+return {
+  {
+    "ellisonleao/gruvbox.nvim",
+    lazy = false,
+    priority = 1000,
+    config = function()
+      -- load colorscheme here
+      vim.o.background = "dark"
+      vim.cmd([[colorscheme gruvbox]])
+    end,
+  },
+}