Convert vim-plug installation to Lua

The `vim-plug` VimScript instructions to install MarkdownPreview are as follows:

```
local vim = vim
local Plug = vim.fn['plug#']

Plug 'iamcco/markdown-preview.nvim', { 'do': { -> mkdp#util#install() }, 'for': ['markdown', 'vim-plug']}

vim.call('plug#end')
```

I'm looking for help on how I can convert the line beginning with `Plug ...` into Lua. This particular line errors out, since Lua does not recognize the data between the curly braces.

The installation guide only shows `.lua` examples for Packer, and I have seen no other discussion after a cursory issue search.

I have tried the following, changing `do` and `for` into `['do']` and `['for']` respectively since both are keywords in Lua, but the same error still surfaces. I suspect the `->` operator might need special handling.

```
Plug 'iamcco/markdown-preview.nvim', { ['do'] = { -> 'mkdp#util#install()' }, ['for'] = {'markdown', 'vim-plug'}}
```

Any help is appreciated!