Fix Number comparison operator docs (#12880)

src/number.cr

@@ -195,7 +195,7 @@ struct Number
   # Returns:
   # - `-1` if `self` is less than *other*
   # - `0` if `self` is equal to *other*
-  # - `-1` if `self` is greater than *other*
+  # - `1` if `self` is greater than *other*
   # - `nil` if `self` is `NaN` or *other* is `NaN`, because `NaN` values are not comparable
   def <=>(other) : Int32?
     # NaN can't be compared to other numbers