docs: fix `lualine` component example

As per https://github.com/LazyVim/LazyVim/issues/4544 it creates
confusion to the users who are just trying out the example to try things
out. Better to avoid such misinterpretations in the future.

I'm assuming this will also update the docs automatically as I can
deduce from
25af26046a/lua/build.lua (L369-L372)?

lua/plugins/example.lua

@@ -157,7 +157,11 @@ return {
     "nvim-lualine/lualine.nvim",
     event = "VeryLazy",
     opts = function(_, opts)
-      table.insert(opts.sections.lualine_x, "😄")
+      table.insert(opts.sections.lualine_x, {
+        function()
+          return "😄"
+        end,
+      })
     end,
   },