Cargo: clarify TODO for tree-sitter update

I went to do this work and then realized we need unreleased support for
tree-sitter 0.24 in tree-sitter-md before we can start on this. Add
a note for clarity.

Author: cpu

Cargo.toml

@@ -24,6 +24,9 @@ hickory-resolver = { version = "=0.25.0-alpha.4", features = ["dns-over-https-ru
 tokio = { version = "1.43.0", features = ["io-util", "macros", "net", "rt"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
-tree-sitter = "0.23" # TODO(@cpu): handle breaking API changes for 0.24
+# TODO(@cpu): handle breaking API changes for tree-sitter 0.24.
+#   This is blocked on a tree-sitter-md release for the tree-sitter 0.24 update
+#   presently unreleased on upstream main.
+tree-sitter = "0.23" 
 tree-sitter-c = "0.23"
 tree-sitter-md = "0.3"