[combobox] Examples of inline single and multi select Combobox

# Docs feedback

## How can we improve Base UI documentation?

I have been working on creating an inline single and multi-select Combobox, and facing quite a few difficulties with building it as I had to dig into the documentation and props for it.

One other thing that I would like to point out is that, you would have to pass in `open` as true, for selection through keyboard to work correctly when `inline`. Is this expected behavior?