refactor: move mdx.nvim and neodim plugins to correct files for better organization

lua/plugins/languages.lua

@@ -136,4 +136,10 @@ return {
             require('treesj').setup()
         end,
     },
+
+    {
+        'davidmh/mdx.nvim',
+        config = true,
+        dependencies = { 'nvim-treesitter/nvim-treesitter' },
+    },
 }