`is_ordered` changes

This is a possible breaking change.

If someone previously use `is_ordered=True` explicitly to ignore ordering, this will break their test cases.

e.g.

```python
import jsonmatch
a = [1, 2, 3]
b = [3, 2, 1]
matcher = jsonmatch.compile(a)
matcher.assert_matches(b, is_ordered=True)
```

Not sure if it is worth to update the code to match up with the doc. If we update doc to match with the code, then we won't break any codes that rely on this behavior.