Add STAAR test prep for texans.

Hi Book (📖) Worm (🪱),

Thank you for sharing your thoughts on the creation of a STAAR course. I will be sure to pass this feedback along to the appropriate team so we can discuss it.

As we grow and expand, we’re continuing to add new content to offer a better education at Khan Academy. Investing more heavily in the content team is actually one of our major initiatives.

Warm regards,