Tricky phrasing in the `collections.Counter` docs

# Documentation

The [collections.Counter documentation](https://docs.python.org/3/library/collections.html#collections.Counter) states:
`c.items()                       # convert to a list of (elem, cnt) pairs`
which seems to have been correct in Python 2 but is no longer "technically" correct



### Linked PRs
* gh-109813