Is there any content about Gravitational-wave astronomy?

It will probably make it to season 2 if they can explain it in a way most people can understand it. Since it is still a new science and they are still developing it they may limit it to an explanation of what it is and what we have discovered about it so far. Maybe like they talked about multiverse theory in the first season.

Why watch Idiocracy when you have a TV and the internet?

Look I don't want to kill you're expectations but Season 2 is not going to happen or at least it's not goning happen any time soon. But if you're interested in diving deeper into these things. There are plenty of resources available.

1. worldscienceu.com (Probably the best, you'll find everything there.)
2. Astronomy Section on Coursera
3. Astrophysics XSeries on edX