The best way to get in touch is on GitHub. If you head over to the brainrender repository you can find more docs, examples and everything else you might need.
You can also open an issue to ask a question about brainrender, to request a new feature or to report a bug. If you'd like to help develop code for brainrender you can fork the repository and submit a pull request with the changes you'd like to propose.
You can also find the main developer behind brainrender on twitter if you'd like to reach out there.