How to install?

Hi,
How does one install this extension into Laravel-Admin?
I've tried:
```
composer require laravel-admin-ext/typeahead
```
But does not work. It returns this error:
```
[InvalidArgumentException]
Could not find a matching version of package laravel-admin-ext/typeahead.
Check the package spelling, your version constraint and that the package is
available in a stability which matches your minimum-stability (dev).
```
Could you extend the readme?
Thank you.

Start with the README and the Composer installation instructions shown in the issue. Check how this Laravel-Admin extension is expected to be installed and document the correct command and setup steps; done means a user can follow the README without receiving the reported package-not-found error.

Written by the indexing model from the issue text.