Update inverted index docs

Marcus Gartner (mgartner) commented:

The [inverted index docs](https://www.cockroachlabs.com/docs/stable/inverted-indexes#arrays] do not list all operators for which inverted indexes on ARRAYs and JSON can be used.

### Arrays

The following operators in filters can use inverted indexes on an ARRAY-type column:

* **is contained by** `<@` (already mentioned in docs)
* **contains** `@>` (already mentioned in docs)
* **overlaps** `&&`
* Do the two arrays have any elements in common?
* Ex: `array_col && ARRAY['foo', 'bar')`

## JSON

* **is contained by** `<@` (already mentioned in docs)
* **contains** `@>` (already mentioned in docs)
* **equals** `=` (already mentioned in docs)
* **exist** `?`
* Does the string exist as a top-level key within the JSON value?
* Ex: `json_col ? 'foo'`
* **some/any exists** `?|`
* Do any of the strings in the array exist as top-level keys?
* Ex: `json_col ?| ARRAY['foo', 'bar']`
* **all exists** ?&'
* Do all of the strings in the array exist as top-level keys?
* Ex: `json_col ?& ARRAY['foo', 'bar']`

It might be worth noting that some more complex JSON expressions with the **fetch value** operator, `->`, can also be index-accelerated. Some examples:

```sql
SELECT * FROM t WHERE json_col->'foo' = '123'::JSON;

SELECT * FROM t WHERE json_col->0->'foo' = '123'::JSON;

SELECT * FROM t WHERE json_col->'foo' @> '[1, 2, 3]'::JSON;

SELECT * FROM t where json_col->'foo' IN ('[1, 2, 3]'::JSON, '{"a": "b"}'::JSON);
```

Jira Issue: DOC-9133