diff --git a/.gitignore b/.gitignore
index 3a62426b..f554f800 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ _build
 _opam
 *.install
 .merlin
+todo.md
diff --git a/src/core/route.mli b/src/core/route.mli
index 7d0c3980..29d54e3d 100644
--- a/src/core/route.mli
+++ b/src/core/route.mli
@@ -54,6 +54,7 @@ val to_string : _ t -> string
     @since 0.7 *)
 
 val to_url : ('a, string) t -> 'a
+(** [to_url route args] takes a route, and turns it into a URL path. *)
 
 module Private_ : sig
   val eval : string list -> ('a, 'b) t -> 'a -> 'b option