Library bugs and improvements

[prasanna1211]

Hey, thanks for the wonderful library. I could almost solve all my usecases. I found a few bugs and improvements that are possible.

Bugs:

1. highlightedOption is mentioned in the API, but it is not currently exposed. It is missed in this commit during the reimplementation with index.

2. In the Docs, there is a small typo

Improvements:

1. Currently, the entire options list is filtered and the result is shown. I would like to add another behaviour where instead of filtering, the list would scroll to the actual index of the first matching element. This is also a widely used approach (react-select) and I believe this would not degrade any existing functionality.

2. Having a ghost element that populates the label of the selected element.

This also can be achieved through a prop without degrading the existing functionality.

Please let me know if these are aligned with your vision for this library. If so we can discuss about the props and I can raise a PR as needed. Thanks