feat(plugins): add heirline

plugins/astrocore/default.nix

@@ -7,6 +7,21 @@
       (import ./package { inherit lib pkgs; })
     ];
 
-    config = "require('astrocore').setup({})";
+    # https://github.com/AstroNvim/AstroNvim/blob/v4.7.7/lua/astronvim/plugins/_astrocore_options.lua#L49-L53
+    config = ''
+      local g = {}
+      g.markdown_recommended_style = 0
+
+      if not vim.t.bufs then vim.t.bufs = vim.api.nvim_list_bufs() end -- initialize buffer list
+
+      require('astrocore').setup({
+        g = {
+          markdown_recommended_style = 0,
+        },
+        t = {
+          bufs = vim.t.bufs,
+        },
+      })
+    '';
   };
 }