fix(examples): fix a bug (#10)

According to documentation and my test, this is the way to add new items to the table

lua/plugins/example.lua

@@ -166,12 +166,10 @@ return {
   {
     "nvim-treesitter/nvim-treesitter",
     opts = function(_, opts)
+      -- add tsx and treesitter
       vim.list_extend(opts.ensure_installed, {
-        -- add tsx and treesitter
-        ensure_installed = {
           "tsx",
           "typescript",
-        },
       })
     end,
   },