fix(builtin.commands): no preview for multiline description commands

[antonk52]

Description

Currently if you have at least one command with multiline description the preview for telescope.builtin.commands() is broken, ie display an empty looking floating picker.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

-- init.lua
vim.api.nvim_create_user_command('Kek', function() end, {
        desc=[[
        foo
        bar
        baz
        ]]
})
require('telescope.builtin').commands()

With this change the commands preview is displayed as expected

Configuration:

• Neovim version (nvim --version): 0.8.1
• Operating system and version: Macos

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[antonk52]

Fixed stylua quotes issue

[Conni2461]

Thanks :)