feat(markdown): added headlines.nvim to markdown extra

lua/lazyvim/plugins/extras/lang/markdown.lua

@@ -61,4 +61,19 @@ return {
       vim.cmd([[do FileType]])
     end,
   },
+
+  {
+    "lukas-reineke/headlines.nvim",
+    opts = function()
+      local opts = {}
+      for _, ft in ipairs({ "markdown", "norg", "rmd", "org" }) do
+        opts[ft] = { headline_highlights = {} }
+        for i = 1, 6 do
+          table.insert(opts[ft].headline_highlights, "Headline" .. i)
+        end
+      end
+      return opts
+    end,
+    ft = { "markdown", "norg", "rmd", "org" },
+  },
 }