Fix typo in Js.Undefined.to_opt deprecation message.

Signed-off-by: Utkarsh Kukreti <utkarshkukreti@gmail.com>

Author: utkarshkukreti

jscomp/runtime/js_undefined.mli

@@ -97,4 +97,4 @@ val from_opt : 'a option -> 'a t
 *)
 external toOption : 'a t -> 'a option = "#undefined_to_opt"
 external to_opt : 'a t -> 'a option = "#undefined_to_opt"
-[@@deprecated "use toOpt instead"]  
+[@@deprecated "use toOption instead"]