Fix a Timsort function helper comment
diff --git a/xpath.c b/xpath.c
index 89da0c8..701696e 100644
--- a/xpath.c
+++ b/xpath.c
@@ -148,7 +148,8 @@
  *
  * Comparison function for the Timsort implementation
  *
- * Returns -2 or +2 based on the order
+ * Returns -2 in case of error -1 if first point < second point, 0 if
+ *         it's the same node, +1 otherwise
  */
 static
 int wrap_cmp( xmlNodePtr x, xmlNodePtr y );