Fix packer.nvim style example config miss

Author: mimikun

README.adoc

@@ -153,7 +153,7 @@ require('jetpack.packer').startup(function(use)
     run = ':TSUpdate',
     config = function()
       require'nvim-treesitter.configs'.setup {
-        ensure_installed = 'maintained',
+        ensure_installed = { "c", "lua", "vim", "vimdoc", "query" },
         highlight = { enable = true }
       }
     end
@@ -181,7 +181,7 @@ require('jetpack.packer').add {
     run = ':TSUpdate',
     config = function()
       require'nvim-treesitter.configs'.setup {
-        ensure_installed = 'maintained',
+        ensure_installed = { "c", "lua", "vim", "vimdoc", "query" },
         highlight = { enable = true }
       }
     end