feat(markdown): replace headlines.nvim by markdown.nvim (#4139)

Okay, so
https://github.com/MeanderingProgrammer/markdown.nvim?tab=readme-ov-file
is a new kid on the block that I've been enjoying a lot. It replaces
headlines.nvim.

This new extra is a way for folks to try markdown.nvim effortlessly.

(Should I add here everything from the current markdown extra to make
this extra a complete drop-in replacement?)

---------

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>

NEWS.md

@@ -2,6 +2,9 @@
 
 ## 12.x
 
+- **Markdown Extra**: [headlines.nvim](https://github.com/lukas-reineke/headlines.nvim) has been removed in favor of [markdown.nvim](https://github.com/MeanderingProgrammer/markdown.nvim)
+  to spice up your markdown files.
+
 - [nvim-spectre](https://github.com/nvim-pack/nvim-spectre) has been removed in favor of [grug-far.nvim](https://github.com/MagicDuck/grug-far.nvim).
   **grug-far.nvim** has a great UI and feels more intuitive to use.
 

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

@@ -92,31 +92,20 @@ return {
   },
 
   {
-    "lukas-reineke/headlines.nvim",
-    opts = function()
-      local opts = {}
-      for _, ft in ipairs({ "markdown", "norg", "rmd", "org" }) do
-        opts[ft] = {
-          headline_highlights = {},
-          -- disable bullets for now. See https://github.com/lukas-reineke/headlines.nvim/issues/66
-          bullets = {},
-          quote_string = false,
-        }
-        for i = 1, 6 do
-          local hl = "Headline" .. i
-          vim.api.nvim_set_hl(0, hl, { link = "Headline", default = true })
-          table.insert(opts[ft].headline_highlights, hl)
-        end
-      end
-      return opts
-    end,
+    "MeanderingProgrammer/markdown.nvim",
+    opts = {
+      file_types = { "markdown", "norg", "rmd", "org" },
+      code = {
+        sign = false,
+        width = "block",
+        right_pad = 1,
+      },
+      heading = {
+        sign = false,
+        icons = {},
+      },
+    },
     ft = { "markdown", "norg", "rmd", "org" },
-    config = function(_, opts)
-      -- PERF: schedule to prevent headlines slowing down opening a file
-      vim.schedule(function()
-        require("headlines").setup(opts)
-        require("headlines").refresh()
-      end)
-    end,
+    enabled = true,
   },
 }