Update markdown highlighting for tree-sitter
diff --git a/modules/neovim/tree-sitter/highlights.scm b/modules/neovim/tree-sitter/highlights.scm
new file mode 100644
index 0000000..a5abd85
--- /dev/null
+++ b/modules/neovim/tree-sitter/highlights.scm
@@ -0,0 +1,27 @@
+;; extends
+
+[
+  (atx_h1_marker)
+  (atx_h2_marker)
+  (atx_h3_marker)
+  (atx_h4_marker)
+  (atx_h5_marker)
+  (atx_h6_marker)
+  (setext_h1_underline)
+  (setext_h2_underline)
+] @punctuation.special.header
+
+[
+  (list_marker_plus)
+  (list_marker_minus)
+  (list_marker_star)
+  (list_marker_dot)
+  (list_marker_parenthesis)
+] @punctuation.special.list
+
+(thematic_break) @punctuation.special.thematic_break
+
+[
+  (block_continuation)
+  (block_quote_marker)
+] @punctuation.special.block_quote