Fix up g_bytes_compare() documentation

It was declaring the opposite of what the function was actually doing,
and what every other comparison function is doing.

glib/gbytes.c

@@ -403,10 +403,18 @@ g_bytes_hash (gconstpointer bytes)
  *
  * Compares the two #GBytes values.
  *
- * This function can be used to sort GBytes instances in lexographical order.
+ * This function can be used to sort GBytes instances in lexicographical order.
+ *
+ * If @bytes1 and @bytes2 have different length but the shorter one is a
+ * prefix of the longer one then the shorter one is considered to be less than
+ * the longer one. Otherwise the first byte where both differ is used for
+ * comparison. If @bytes1 has a smaller value at that position it is
+ * considered less, otherwise greater than @bytes2.
+ *
+ * Returns: a negative value if @bytes1 is less than @bytes2, a positive value
+ *          if @bytes1 is greater than @bytes2, and zero if @bytes1 is equal to
+ *          @bytes2
  *
- * Returns: a negative value if bytes2 is lesser, a positive value if bytes2 is
- *          greater, and zero if bytes2 is equal to bytes1
  *
  * Since: 2.32
  */