added markdown preview plugin

.config/nvim/lua/plugins.lua

@@ -153,6 +153,10 @@ return require('packer').startup(function()
          require('other').autosession()
       end
    }
+   use {
+      'ellisonleao/glow.nvim',
+      ft = { 'md', 'markdown', }
+   }
 
    -- Conveniences
    use {                                           -- Undo tree