treefmt: add mdformat for markdown files

formatter.nix

@@ -7,6 +7,7 @@
       treefmt.projectRootFile = "LICENSE.md";
       treefmt.programs.shellcheck.enable = true;
 
+      treefmt.programs.mdformat.enable = true;
       treefmt.programs.mypy.enable = true;
       treefmt.programs.nixfmt.enable = true;
       treefmt.programs.nixfmt.package = pkgs.nixfmt-rfc-style;
@@ -37,8 +38,6 @@
         "*/gnupg-home/*"
         "*/sops/secrets/*"
         "vars/*"
-        # prettier messes up our mkdocs flavoured markdown
-        "*.md"
         "**/node_modules/*"
         "**/.mypy_cache/*"
 
@@ -96,6 +95,8 @@
         ];
         excludes = [
           "*/asciinema-player/*"
+          # prettier messes up our mkdocs flavoured markdown
+          "*.md"
         ];
       };
       treefmt.programs.mypy.directories = {