docs: show a luarocks badge in the readme

Hello Luarocks! yazi.nvim can now be used using Neovim package managers
that can use Luarocks as a source.

<https://luarocks.org/modules/mikavilpas/yazi.nvim>

README.md

@@ -3,6 +3,7 @@
 <a href="https://dotfyle.com/plugins/mikavilpas/yazi.nvim">
   <img src="https://dotfyle.com/plugins/mikavilpas/yazi.nvim/shield?style=flat-square" alt="shield image for plugin usage" /> </a>
 
+![LuaRocks](https://img.shields.io/luarocks/v/mikavilpas/yazi.nvim)
 [![Type checked codebase](https://github.com/mikavilpas/yazi.nvim/actions/workflows/typecheck.yml/badge.svg)](https://github.com/mikavilpas/yazi.nvim/actions/workflows/typecheck.yml)
 
 Yazi is a blazing fast file manager for the terminal. This plugin allows you to